MCP (Model Context Protocol)

MCP lets Nastech Agent connect to external tool servers so the agent can use tools that live outside Nastech itself — GitHub, databases, file systems, browser stacks, internal APIs, and more.

If you have ever wanted Nastech to use a tool that already exists somewhere else, MCP is usually the cleanest way to do it.

Coming from Claude Code?

The mcpServers block in your ~/.claude.json maps to mcp_servers in Nastech' config.yaml — and nastech import-agent claude-code migrates it (along with skills and instructions) automatically. See Import from Other Agents.

What MCP gives you

Access to external tool ecosystems without writing a native Nastech tool first
Local stdio servers and remote HTTP MCP servers in the same config
Automatic tool discovery and registration at startup
Utility wrappers for MCP resources and prompts when supported by the server
Per-server filtering so you can expose only the MCP tools you actually want Nastech to see

Quick start

MCP support ships with the standard install — no extra step needed.
Add an MCP server to ~/.nastech/config.yaml:

mcp_servers:
  filesystem:
    command: "npx"
    args: ["-y", "@modelcontextprotocol/server-filesystem", "/home/user/projects"]

Start Nastech:

nastech chat

Ask Nastech to use the MCP-backed capability.

For example:

List the files in /home/user/projects and summarize the repo structure.

Nastech will discover the MCP server's tools and use them like any other tool.

Catalog: one-click install for Nastech-approved MCPs

Nastech ships a curated catalog of MCP servers that Nastech staff has reviewed and merged. They're disabled by default — install only what you actually want.

In the desktop app you can also ask: "add the Linear MCP". The agent calls manage_connections with an mcp: true target, an approval card appears in the chat, and Install writes the same config the CLI would. On the CLI and in messaging apps the agent relays the commands below instead.

nastech mcp                # interactive picker (default)
nastech mcp catalog        # plain-text list, scriptable
nastech mcp install n8n    # install a catalog entry by name

The picker shows each entry with its current status:

n8n          available              Manage and inspect n8n workflows from Nastech
linear       enabled                Linear issue/project management (remote OAuth)
github       installed (disabled)   GitHub repo + PR tools

Hit Enter on a row to install (and walk through any required credentials), enable, disable, or uninstall. Catalog entries are stored under optional-mcps/ in the nastech-agent repo — presence in that directory means Nastech approval. There is no community submission tier; entries are added by merging a PR.

Catalog entries can require:

API key — Nastech prompts at install time and writes the value to ~/.nastech/.env. Non-secret values (base URLs) go to the same file.
OAuth (remote MCP) — written as auth: oauth in your config; the MCP client opens a browser on first connection.
OAuth (third-party provider like Google/GitHub) — Nastech points you at nastech auth <provider> if you haven't authenticated already.

Tool selection at install time

After credentials are configured, Nastech probes the MCP server to list every tool it exposes and presents a checklist:

Select tools for 'linear' (SPACE toggle, ENTER confirm)
  [x] find_issues       Find issues matching a query
  [x] get_issue         Get a single issue
  [x] create_issue      Create a new issue
  [ ] delete_workspace  Delete a Linear workspace
  ...

The pre-checked rows come from:

Your prior selection if you've installed this entry before (reinstalls preserve what you had — the manifest's defaults don't override it)
The manifest's tools.default_enabled if the entry declares one (some catalog entries pre-prune mutating or rarely-useful tools)
Everything if neither applies

Some entries with very large auto-generated surfaces (e.g. cloudflare, ~3,300 OpenAPI endpoint tools) instead declare tools.default_excluded — a curated block-list of names and glob patterns. Installing one of these skips the checklist entirely and writes tools.exclude; everything not matched stays enabled, including tools the server adds later. Edit mcp_servers.<name>.tools.exclude in config.yaml to re-enable a family.

Submit the checklist with ENTER. Only the checked tools end up in mcp_servers.<name>.tools.include. If you select everything, no filter is written (cleanest config shape, identical behavior).

If the probe fails (server unreachable, OAuth not yet completed, backing service not running), the install still succeeds: the manifest's tools.default_enabled is applied directly (if declared), or no filter is written (if not). Re-run nastech mcp configure <name> once the server is reachable to refine.

Trust model

Installing a catalog entry runs whatever the manifest specifies — git clone, the entry's bootstrap commands (pip install, npm install, etc.), and ultimately the MCP server's own code. Manifests are gated by PR review into the nastech-agent repo, so Nastech has reviewed each entry before it shipped — but you should still read the manifest before installing, especially the source: field's repository, the install.bootstrap: commands, and any transport.command: invocation.

Manifests live at optional-mcps/<name>/manifest.yaml on GitHub. The picker also prints the manifest's source: URL at install time so you can quickly verify the upstream repo. The web dashboard's MCP page surfaces the same detail per catalog entry — transport, auth type, the endpoint URL (HTTP) or command + args (stdio), the git install source/ref and bootstrap commands, and setup notes — with the source: rendered as a clickable link, so you can inspect exactly what an entry connects to or runs before clicking Install.

Manifest version compatibility

Manifests pin a manifest_version. The catalog is forward-compatible: if a PR adds an entry with a newer manifest_version than your installed Nastech understands, the picker will surface a warning (⚠ '<name>' requires a newer Nastech) for that entry instead of silently hiding it. Run nastech update to install the latest Nastech when you see that.

Runtime `${ENV_VAR}` substitution

Inside an entry's transport.command, transport.args, transport.url, and headers, ${VAR} placeholders are resolved at server-connect time from environment variables (which include everything in ~/.nastech/.env). This is useful when a catalog entry wants to reference a value the user configured elsewhere — e.g. ${HOME}/foo or ${MY_PROVIDER_TOKEN}.

Cursor-style context variables are also substituted (case-sensitive): ${userHome} (home directory), ${workspaceFolder} (session workspace root), ${workspaceFolderBasename}, and ${pathSeparator} / ${/} (the OS path separator). See the MCP config reference for details.

Note this is distinct from ${INSTALL_DIR} in catalog manifests, which is substituted at install-time with the path the catalog cloned the entry's repo into.

Entries that need your own OAuth app (no DCR)

Some vendors run their remote MCP behind OAuth but do not offer Dynamic Client Registration — every client must be an app the user pre-registers in the vendor's developer console. Asana's V2 server (https://mcp.asana.com/v2/mcp) is the shipped example: the retired V1 https://mcp.asana.com/sse server accepted any client; V2 does not.

Such a manifest declares the credentials under auth.env and pins the client under auth.oauth, so installing it (CLI picker, web dashboard or Desktop) prompts for the Client ID / Client secret, stores them in the profile's .env, and writes only ${VAR} references to config.yaml:

mcp_servers:
  asana:
    url: https://mcp.asana.com/v2/mcp
    auth: oauth
    oauth:
      client_id: "${ASANA_CLIENT_ID}"
      client_secret: "${ASANA_CLIENT_SECRET}"
      redirect_host: localhost      # the vendor matches the redirect URL exactly
      redirect_port: 27890          # register http://localhost:27890/callback on the app

Read the entry's post_install notes for the exact app type and redirect URL to register, then run nastech mcp login <name> and restart (or /reload-mcp) the session or gateway that should expose the tools. The dashboard / Desktop Authorize button works too: because the client is pre-registered with a pinned redirect_port, Nastech keeps the registered loopback callback (http://localhost:27890/callback) instead of the dashboard's own callback URL — so the browser you approve in must run on the same machine as the Nastech process. For a remote host, use nastech mcp login over SSH port-forwarding.

Updating tool selection later

nastech mcp configure linear

Reopens the same checklist with your current selection pre-checked. Use this when you want more tools enabled, or when the server has added new tools that you want to opt into.

Updating the catalog manifest

MCPs are never auto-updated. Re-run nastech mcp install <name> to refresh after a Nastech update if a manifest version changed.

To add an MCP to the catalog, open a PR against optional-mcps/.

Suggestion metadata (`suggest:`)

A manifest may declare an optional suggest: block with keywords: and/or hosts: lists. UI surfaces (currently the Desktop app's composer) use it to offer a one-click "Add <server>" pill when your draft mentions one of the keywords as a completed word, or contains a pasted link whose hostname ends with one of the host suffixes. It is purely advisory — installs still flow through the same validated catalog/config paths — and most hosted remote entries (Atlassian, Sentry, Notion, Stripe, Vercel, Supabase, and friends) declare it.

GitHub is deliberately not in the catalog: its hosted MCP requires each client to bring its own OAuth app (generic dynamic client registration is rejected), and Nastech's bundled github/* skills driving the gh CLI are a more capable integration. On Desktop, GitHub mentions instead offer the github-auth skill when gh isn't signed in yet.

Two kinds of MCP servers

Stdio servers

Stdio servers run as local subprocesses and talk over stdin/stdout.

mcp_servers:
  github:
    command: "npx"
    args: ["-y", "@modelcontextprotocol/server-github"]
    env:
      GITHUB_PERSONAL_ACCESS_TOKEN: "***"

Use stdio servers when:

the server is installed locally
you want low-latency access to local resources
you are following MCP server docs that show command, args, and env

HTTP servers

HTTP MCP servers are remote endpoints Nastech connects to directly.

mcp_servers:
  remote_api:
    url: "https://mcp.example.com/mcp"
    headers:
      Authorization: "Bearer ***"

Use HTTP servers when:

the MCP server is hosted elsewhere
your organization exposes internal MCP endpoints
you do not want Nastech spawning a local subprocess for that integration

HTTP and SSE servers honor the standard proxy settings: HTTPS_PROXY / HTTP_PROXY / ALL_PROXY (a socks:// alias is normalized to socks5://), then the OS proxy (Windows registry, macOS system settings), with NO_PROXY hosts — including CIDR ranges and *.example.com patterns — connecting directly.

OAuth-authenticated HTTP servers

Most hosted MCP servers (Cloudflare, Linear, Sentry, Atlassian, Asana, Figma, Stripe, …) require OAuth 2.1 instead of a static bearer token. Set auth: oauth and Nastech handles discovery, client identification, PKCE, token exchange, refresh, and step-up auth via the MCP Python SDK.

Nastech identifies itself with a Client ID Metadata Document on servers that support one, and falls back to Dynamic Client Registration on those that don't. Both are automatic; there is nothing to configure.

Figma remote MCP

Figma's hosted endpoint (https://mcp.figma.com/mcp) allowlists Dynamic Client Registration by exact client_name — bare "Nastech Agent" 403s, while "Claude Code" and "Codex" succeed. Nastech auto-sets oauth.client_name: "Claude Code" for mcp.figma.com so install/login works without a special trick:

mcp_servers:
  figma:
    url: "https://mcp.figma.com/mcp"
    auth: oauth

Or: nastech mcp install figma, then nastech mcp login figma.

mcp_servers:
  linear:
    url: "https://mcp.linear.app/mcp"
    auth: oauth

On first connect, Nastech prints an authorize URL, opens your browser when possible, and waits for the OAuth callback on a local loopback port. Tokens are cached at ~/.nastech/mcp-tokens/<server>.json with 0o600 perms; subsequent runs reuse them silently until refresh fails.

Refresh tokens are bound to the authorization server that granted them: Nastech records the discovered issuer alongside the cached tokens and, if a server's advertised authorization server ever changes (server migration, metadata edit, or hijack), the stored refresh token is dropped instead of being sent to the new issuer. The current access token keeps working until it expires, then a normal re-authorization runs against the new issuer.

The redirect back from the authorization server is checked against RFC 9207: when the server's metadata advertises authorization_response_iss_parameter_supported, a redirect without a matching iss is rejected. Figma's authorization server (https://api.figma.com) advertises that support and then omits iss; Nastech fills the missing value from the discovered issuer for that one issuer and logs a warning, so nastech mcp login figma completes. A present-but-different iss is still rejected, and no other server gets the exemption.

Remote / headless hosts. When Nastech runs on a different machine than your browser, the loopback callback can't reach your laptop. Ways to complete the flow:

Nastech Desktop (automatic): when you run the OAuth sign-in from the Desktop app's MCP setup UI against a remote backend, Desktop hosts the callback listener on your machine and relays the authorization back to the gateway automatically — no tunnel, paste, or proxy needed. Requires both the Desktop app and the backend to be up to date.
Paste-back (no setup): on an interactive terminal Nastech prints "Or paste the redirect URL here…" alongside the authorize URL. Open the URL in your browser, approve, copy the full URL the browser ends up on (the redirect will show a connection error — that's expected), paste it at the prompt. Bare ?code=…&state=… query strings work too.
Device-code login (no callback at all): if the server's authorization server advertises a device authorization endpoint, run nastech mcp login <server> --flow device on the machine running Nastech. It prints a verification URL and a short code; open the URL on any device, enter the code, and Nastech polls for approval. No browser is launched on the host and no callback listener is needed. Set oauth.flow: device on the server to make login and reauth use it by default. Details: Device-code login.
SSH port forward: ssh -N -L <port>:127.0.0.1:<port> user@host in a separate terminal, then let the redirect flow normally.
Proxied callback (redirect_uri): when a public HTTPS endpoint forwards to the host (e.g. a Tailscale Funnel or reverse proxy pointed at the callback port), set oauth.redirect_uri and the browser redirect reaches Nastech on its own — no tunnel or paste needed:

mcp_servers:
  myserver:
    url: "https://mcp.example.com/mcp"
    auth: oauth
    oauth:
      redirect_port: 8765                                # fixed port for the proxy to target
      redirect_uri: "https://oauth.example.ts.net/callback"

For fully headless gateways (messaging bot, no interactive terminal at all), the optional mcp-oauth-remote-gateway skill walks the agent through completing the flow manually and writing tokens where Nastech expects them.

Pitfall — WAF rejects 127.0.0.1 redirect URIs. A few providers front their authorization server with a WAF that 403s any authorize request whose query string contains a literal 127.0.0.1 (Reclaim.ai's AWS API Gateway is a known example — every attempt returns {"message":"Forbidden"} before reaching the OAuth app). Set oauth.redirect_host: localhost to use http://localhost:<port>/callback instead; the callback listener still binds 127.0.0.1 either way.

See OAuth over SSH / Remote Hosts for the full walkthrough, including DCR-less servers (e.g. Slack), pre-registered client_id/client_secret, scope customization, and re-auth via nastech mcp login <server>.

Pitfall — providers that don't support automatic registration (Google Drive, Atlassian). Some servers reject the dynamic client registration step (RFC 7591) that bare auth: oauth relies on — Google's official Drive server (https://drivemcp.googleapis.com/mcp/v1) returns a 400 Bad Request, so no OAuth client is created and no token is acquired. The symptom is subtle: these servers also serve tools/list without auth, so nastech mcp login can list the tools and look like it worked, but every real tool call later times out. nastech mcp login now detects this (it checks that a token actually landed on disk) and tells you to supply your own OAuth client. Create one in the provider's console and add it to config:

mcp_servers:
  googledrive:
    url: "https://drivemcp.googleapis.com/mcp/v1"
    auth: oauth
    oauth:
      client_id: "<your-oauth-client-id>"
      client_secret: "<your-oauth-client-secret>"

Then run nastech mcp login googledrive — with the pre-registered client, Nastech skips registration and runs the normal browser authorization flow.

Pitfall — config auto-reload race. When you edit ~/.nastech/config.yaml from inside a running Nastech session, the CLI auto-reloads MCP connections with a 30s timeout. That's not enough for an interactive OAuth flow. Add the entry, then run nastech mcp login <server> from a fresh terminal — it waits the full 5 minutes for you to complete auth.

mTLS / client certificates

Remote HTTP MCP servers that require mutual TLS (client-certificate authentication) are supported via client_cert / client_key. Nastech passes the resolved certificate to the underlying HTTP client for the TLS handshake.

client_cert accepts three shapes:

A single combined PEM path — one file holding both the certificate and the private key:

mcp_servers:
  internal_api:
    url: "https://mcp.internal.example.com/mcp"
    client_cert: "~/.certs/mcp-client.pem"

A [cert, key] 2-tuple — certificate and key in separate files (equivalent to setting client_cert + client_key):

mcp_servers:
  internal_api:
    url: "https://mcp.internal.example.com/mcp"
    client_cert: ["~/.certs/mcp-client.crt", "~/.certs/mcp-client.key"]

A [cert, key, password] 3-tuple — when the private key is encrypted, the third element is the key passphrase:

mcp_servers:
  internal_api:
    url: "https://mcp.internal.example.com/mcp"
    client_cert: ["~/.certs/mcp-client.crt", "~/.certs/mcp-client.key", "${MCP_KEY_PASSWORD}"]

You can also keep the cert and key fully separate via client_cert (combined PEM) plus an explicit client_key. Paths support ~ expansion; a missing file raises a clear, server-scoped error rather than an opaque TLS handshake failure.

Per-user identity header

Remote HTTP/SSE MCP servers that key behavior on a caller identity (per-user rate limits, audit trails, multi-tenant routing) can be sent an identity header on every request via identity_header:

mcp_servers:
  team_api:
    url: "https://mcp.team.example.com/mcp"
    identity_header:
      name: "X-User-Id"
      value_from: "static"   # "static" (default) or "profile"
      value: "alice"         # required for static

value_from: static sends the literal value from config.yaml.
value_from: profile sends the active Nastech profile name, resolved once at connect time — useful when multiple profiles on one machine talk to the same server and it needs to tell them apart.

An explicit entry in the server's headers mapping with the same name (any casing) always wins; the identity header never overrides your own header config. Invalid identity_header blocks are warned about and ignored — they never block the server from connecting. On stdio servers the key is ignored with a warning (stdio transports have no headers).

Basic configuration reference

Nastech reads MCP config from ~/.nastech/config.yaml under mcp_servers.

Common keys

Key	Type	Meaning
`command`	string	Executable for a stdio MCP server
`args`	list	Arguments for the stdio server
`env`	mapping	Environment variables passed to the stdio server
`cwd`	string	Working directory for the stdio server process. Default: the session working directory when one is pinned (ACP/gateway sessions, `terminal.cwd`), else the Nastech process directory
`url`	string	HTTP MCP endpoint
`headers`	mapping	HTTP headers for remote servers
`client_cert`	string \| list	Client certificate for mTLS — a combined PEM path, or `[cert, key]` / `[cert, key, password]`
`client_key`	string	Client private-key PEM path (when separate from `client_cert`)
`identity_header`	mapping	Optional per-user identity header for HTTP/SSE servers — `{name, value_from: static\|profile, value}`
`timeout`	number	Tool call timeout
`connect_timeout`	number	Initial connection timeout (also bounds the MCP `initialize` handshake)
`lazy`	bool	If `true`, register the server's tools from the schema cache at startup and only start/connect it on the first tool call (default `false`). Needs one prior live connect to fill the cache.
`idle_timeout_seconds`	number	Recycle a stdio server after this many seconds without a tool call (`0` = never, default). The server restarts transparently on the next tool call.
`max_lifetime_seconds`	number	Recycle a stdio server after this total age (`0` = never, default). Restarts transparently on next use.
`enabled`	bool	If `false`, Nastech skips the server entirely
`supports_parallel_tool_calls`	bool	If `true`, tools from this server may run concurrently
`tools`	mapping	Per-server tool filtering and utility policy

Minimal stdio example

mcp_servers:
  filesystem:
    command: "npx"
    args: ["-y", "@modelcontextprotocol/server-filesystem", "/tmp"]

Recycling memory-heavy stdio servers

Browser-based MCP servers (e.g. @playwright/mcp) keep a full Chromium resident after their first tool call — hundreds of MB that never get released. Opt in to automatic recycling and the server is torn down after the idle/lifetime limit, then restarted transparently the next time one of its tools is called (its tools stay registered the whole time):

mcp_servers:
  playwright:
    command: "npx"
    args: ["-y", "@playwright/mcp@latest", "--headless"]
    idle_timeout_seconds: 900     # recycle after 15 min without a tool call
    max_lifetime_seconds: 86400   # and at least once a day regardless

Minimal HTTP example

mcp_servers:
  company_api:
    url: "https://mcp.internal.example.com"
    headers:
      Authorization: "Bearer ***"

Built-in presets

For well-known MCP servers, nastech mcp add accepts a --preset flag that fills in the transport details so you don't have to look up the command and args. The preset only supplies defaults — anything else (env vars, headers, filtering) you pass on the same command line still wins.

Preset	What it wires up
`codex`	The Codex CLI's MCP server (`codex mcp-server` over stdio). Requires the `codex` CLI on PATH.

# Add Codex CLI as an MCP server in one line
nastech mcp add codex --preset codex

That writes the equivalent of:

mcp_servers:
  codex:
    command: "codex"
    args: ["mcp-server"]

You can pick any local name (nastech mcp add my-codex --preset codex is fine); the preset only provides the command/args defaults.

How Nastech registers MCP tools

Nastech prefixes MCP tools so they do not collide with built-in names:

mcp_<server_name>_<tool_name>

Examples:

Server	MCP tool	Registered name
`filesystem`	`read_file`	`mcp_filesystem_read_file`
`github`	`create-issue`	`mcp_github_create_issue`
`my-api`	`query.data`	`mcp_my_api_query_data`

In practice, you usually do not need to call the prefixed name manually — Nastech sees the tool and chooses it during normal reasoning.

Tool-result sanitization and `_meta`

Two behaviors apply to every MCP tool result before the model sees it:

Invisible Unicode TAG characters are stripped. Characters in the U+E0000–U+E007F range render as nothing in terminals and chat UIs but are fully visible to the model — a classic prompt-injection smuggling channel for a malicious or compromised server. Nastech strips them from tool results, resource content, and tool descriptions. Legitimate emoji tag sequences (regional flags like 🏴󠁧󠁢󠁳󠁣󠁴󠁿) are preserved.
Vendor _meta is surfaced; protocol-reserved keys are not. When a server attaches a _meta mapping to a tool result (vendor namespaces like com.example/handoff), Nastech passes it through to the model alongside the result content. Keys under protocol-reserved prefixes — a modelcontextprotocol or mcp label followed by another label, e.g. modelcontextprotocol.io/... or tools.mcp.com/... — are dropped, matching the MCP spec's key-name rules. If nothing model-facing remains, the _meta field is omitted entirely.

MCP utility tools

When supported, Nastech also registers utility tools around MCP resources and prompts:

list_resources
read_resource
list_prompts
get_prompt

These are registered per server with the same prefix pattern, for example:

mcp_github_list_resources
mcp_github_get_prompt

Important

These utility tools are now capability-aware:

Nastech only registers resource utilities if the MCP session actually supports resource operations
Nastech only registers prompt utilities if the MCP session actually supports prompt operations

So a server that exposes callable tools but no resources/prompts will not get those extra wrappers.

Per-server filtering

You can control which tools each MCP server contributes to Nastech, allowing fine-grained management of your tool namespace.

Disable a server entirely

mcp_servers:
  legacy:
    url: "https://mcp.legacy.internal"
    enabled: false

If enabled: false, Nastech skips the server completely and does not even attempt a connection.

Whitelist server tools

mcp_servers:
  github:
    command: "npx"
    args: ["-y", "@modelcontextprotocol/server-github"]
    env:
      GITHUB_PERSONAL_ACCESS_TOKEN: "***"
    tools:
      include: [create_issue, list_issues]

Only those MCP server tools are registered.

Entries in include/exclude may also be glob patterns (*, ?, [...], matched case-sensitively): include: ["*_dns_*"] registers every tool whose name contains _dns_. Plain entries without metacharacters stay exact-match. Globs are the practical way to filter servers that expose thousands of auto-generated endpoint tools by product family.

Blacklist server tools

mcp_servers:
  stripe:
    url: "https://mcp.stripe.com"
    tools:
      exclude: [delete_customer]

All server tools are registered except the excluded ones.

Glob patterns

Both lists accept fnmatch-style globs alongside exact names — essential for huge flat surfaces like Cloudflare's API MCP (?codemode=false, ~3,300 tools) where excluding product areas one endpoint at a time is impractical:

mcp_servers:
  cloudflare:
    url: "https://mcp.cloudflare.com/mcp?codemode=false"
    auth: oauth
    tools:
      exclude: ["*_radar_*", "*_accounts_dlp_*", "*_zones_web3_*"]

Entries without glob metacharacters (*, ?, [) match exactly — docs excludes only the tool named docs, never docs_search.

Precedence rule

If both are present:

tools:
  include: [create_issue]
  exclude: [create_issue, delete_issue]

include wins.

Filter utility tools too

You can also separately disable Nastech-added utility wrappers:

mcp_servers:
  docs:
    url: "https://mcp.docs.example.com"
    tools:
      prompts: false
      resources: false

That means:

tools.resources: false disables list_resources and read_resource
tools.prompts: false disables list_prompts and get_prompt

Full example

mcp_servers:
  github:
    command: "npx"
    args: ["-y", "@modelcontextprotocol/server-github"]
    env:
      GITHUB_PERSONAL_ACCESS_TOKEN: "***"
    tools:
      include: [create_issue, list_issues, search_code]
      prompts: false

  stripe:
    url: "https://mcp.stripe.com"
    headers:
      Authorization: "Bearer ***"
    tools:
      exclude: [delete_customer]
      resources: false

  legacy:
    url: "https://mcp.legacy.internal"
    enabled: false

What happens if everything is filtered out?

If your config filters out all callable tools and disables or omits all supported utilities, Nastech does not create an empty runtime MCP toolset for that server.

That keeps the tool list clean.

Runtime behavior

Discovery time

Nastech discovers MCP servers at startup and registers their tools into the normal tool registry.

Lazy start

A server with lazy: true is registered from the on-disk schema cache instead: its tools appear in the registry immediately, and the process is spawned (or the HTTP endpoint connected) on the first tool call. The cache is written on every live connect, so the first run of a new or changed server is always eager. The banner and the TUI session panel show such a server as lazy with its cached tool count (3 tool(s) (lazy, starts on first use)) — it is a working server, not a failed one — and the startup discovery summary counts it as N lazy, not spawned yet.

Dynamic Tool Discovery

MCP servers can notify Nastech when their available tools change at runtime by sending a notifications/tools/list_changed notification. When Nastech receives this notification, it automatically re-fetches the server's tool list and updates the registry — no manual /reload-mcp required.

This is useful for MCP servers whose capabilities change dynamically (e.g. a server that adds tools when a new database schema is loaded, or removes tools when a service goes offline).

The refresh is lock-protected so rapid-fire notifications from the same server don't cause overlapping refreshes. Prompt and resource change notifications (prompts/list_changed, resources/list_changed) are received but not yet acted on.

Reloading

If you change MCP config, use:

/reload-mcp

This reloads MCP servers from config and refreshes the available tool list. It is also the explicit way to re-probe availability-gated tools (Docker, HASS_TOKEN, OAuth…): a session's tool set is otherwise frozen, so a credential or daemon that appears mid-session is only picked up on /reload-mcp, /new, or context compaction. For runtime tool changes pushed by the server itself, see Dynamic Tool Discovery above.

A running messaging gateway (nastech gateway run) also watches config.yaml on its own: within about a minute of you removing an mcp_servers entry or setting enabled: false, that server's connection is torn down; a newly added entry is connected. A server whose first connect failed (an unreachable host, or an OAuth server on a headless box that had no token yet) is retried automatically on its connect cooldown schedule (30 s, doubling up to 10 min) once you fix the cause. No restart or /reload-mcp needed for the edit to take effect.

Expired OAuth tokens in the background. The gateway, /reload-mcp, and the periodic self-probe of a parked server never open a browser — nobody is there to complete the flow. When a refresh token dies, the server parks with a warning in gateway.log and you re-authorize once with nastech mcp login <server> (or the Desktop/dashboard Authorize button); the parked server picks the new token up on its next probe.

Toolsets

Each configured MCP server also creates a runtime toolset when it contributes at least one registered tool:

mcp-<server>

That makes MCP servers easier to reason about at the toolset level.

Security model

Stdio env filtering

For stdio servers, Nastech does not blindly pass your full shell environment.

Only explicitly configured env plus a safe baseline are passed through. This reduces accidental secret leakage.

Config-level exposure control

The new filtering support is also a security control:

disable dangerous tools you do not want the model to see
expose only a minimal whitelist for a sensitive server
disable resource/prompt wrappers when you do not want that surface exposed

Example use cases

GitHub server with a minimal issue-management surface

mcp_servers:
  github:
    command: "npx"
    args: ["-y", "@modelcontextprotocol/server-github"]
    env:
      GITHUB_PERSONAL_ACCESS_TOKEN: "***"
    tools:
      include: [list_issues, create_issue, update_issue]
      prompts: false
      resources: false

Use it like:

Show me open issues labeled bug, then draft a new issue for the flaky MCP reconnection behavior.

Stripe server with dangerous actions removed

mcp_servers:
  stripe:
    url: "https://mcp.stripe.com"
    headers:
      Authorization: "Bearer ***"
    tools:
      exclude: [delete_customer, refund_payment]

Use it like:

Look up the last 10 failed payments and summarize common failure reasons.

Filesystem server for a single project root

mcp_servers:
  project_fs:
    command: "npx"
    args: ["-y", "@modelcontextprotocol/server-filesystem", "/home/user/my-project"]

Use it like:

Inspect the project root and explain the directory layout.

Troubleshooting

MCP server not connecting

Check:

# Verify MCP deps are installed (already included in standard install)
cd ~/.nastech/nastech-agent && uv pip install -e ".[mcp]"

node --version
npx --version

Then verify your config and restart Nastech.

Remote (HTTP) server rejects the connection

nastech mcp test <name> reports what the server actually answered. When the MCP SDK can only say Server returned an error response (a 4xx/5xx whose body is not a JSON-RPC error), Nastech appends the HTTP status, the URL it requested and the start of the response body:

Streamable HTTP: Server returned an error response (HTTP 400 from POST http://host:27200/mcp:
{"jsonrpc":"2.0","error":{"code":-32020,"message":"Unsupported MCP-Protocol-Version"}})

Read the status and body first: a 400/405 on the initialize POST usually means the endpoint speaks SSE only (set transport: sse) or a proxy in front of it rejects the request; a 401/403 means the token or OAuth grant is wrong; an HTML body means the URL points at a web page, not an MCP endpoint. nastech logs --level debug additionally shows the exact endpoint each connect attempt used.

Tools not appearing

Possible causes:

the server failed to connect
discovery failed
your filter config excluded the tools
the utility capability does not exist on that server
the server is disabled with enabled: false

If you are intentionally filtering, this is expected.

Why didn't resource or prompt utilities appear?

Because Nastech now only registers those wrappers when both are true:

your config allows them
the server session actually supports the capability

This is intentional and keeps the tool list honest.

Parallel Tool Calls

By default, MCP tools run sequentially — one at a time. If your MCP server exposes tools that are safe to run concurrently (e.g. read-only queries, independent API calls), you can opt-in to parallel execution:

mcp_servers:
  docs:
    command: "docs-server"
    supports_parallel_tool_calls: true

When supports_parallel_tool_calls is true, Nastech may execute multiple tools from that server at the same time within a single tool-call batch, just like it does for built-in read-only tools (web_search, read_file, etc.).

caution

Only enable parallel calls for MCP servers whose tools are safe to run at the same time. If tools read and write shared state, files, databases, or external resources, review the read/write race conditions before enabling this setting.

MCP Sampling Support

MCP servers can request LLM inference from Nastech via the sampling/createMessage protocol. This allows an MCP server to ask Nastech to generate text on its behalf — useful for servers that need LLM capabilities but don't have their own model access.

Sampling is enabled by default for all MCP servers (when the MCP SDK supports it). Configure it per-server under the sampling key:

mcp_servers:
  my_server:
    command: "my-mcp-server"
    sampling:
      enabled: true            # Enable sampling (default: true)
      model: "openai/gpt-4o"  # Override model for sampling requests (optional)
      max_tokens_cap: 4096     # Max tokens per sampling response (default: 4096)
      timeout: 30              # Timeout in seconds per request (default: 30)
      max_rpm: 10              # Rate limit: max requests per minute (default: 10)
      max_tool_rounds: 5       # Max tool-use rounds in sampling loops (default: 5)
      allowed_models: []       # Allowlist of model names the server may request (empty = any)
      log_level: "info"        # Audit log level: debug, info, or warning (default: info)

The sampling handler includes a sliding-window rate limiter, per-request timeouts, and tool-loop depth limits to prevent runaway usage. Metrics (request count, errors, tokens used) are tracked per server instance.

To disable sampling for a specific server:

mcp_servers:
  untrusted_server:
    url: "https://mcp.example.com"
    sampling:
      enabled: false

MCP Elicitation Support

MCP servers can ask the user for structured input mid-tool-call via the elicitation/create protocol (mcp Python SDK ≥ 1.11.0). Nastech routes form-mode elicitations through its existing approval surface — an interactive prompt in the CLI/TUI, or approval buttons on gateway platforms like Telegram and Slack — so the request reaches you wherever the session lives. URL-mode elicitations (where a server points you at an external URL) are declined as unsupported.

Elicitation is enabled by default per server. Configure it under the elicitation key:

mcp_servers:
  my_server:
    command: "my-mcp-server"
    elicitation:
      enabled: true    # default: true
      timeout: 300     # seconds to wait for your answer (default: 300)

The 5-minute default timeout mirrors the gateway approval default so users on async surfaces have time to respond before the server gives up. Per-server metrics (requests, accepted, declined, errors) are tracked on the handler.

Running Nastech as an MCP server

In addition to connecting to MCP servers, Nastech can also be an MCP server. This lets other MCP-capable agents (Claude Code, Cursor, Codex, or any MCP client) use Nastech's messaging capabilities — list conversations, read message history, and send messages across all your connected platforms.

When to use this

You want Claude Code, Cursor, or another coding agent to send and read Telegram/Discord/Slack messages through Nastech
You want a single MCP server that bridges to all of Nastech's connected messaging platforms at once
You already have a running Nastech gateway with connected platforms

Quick start

nastech mcp serve

This starts a stdio MCP server. The MCP client (not you) manages the process lifecycle.

MCP client configuration

Add Nastech to your MCP client config. For example, in Claude Code's ~/.claude/claude_desktop_config.json:

{
  "mcpServers": {
    "nastech": {
      "command": "nastech",
      "args": ["mcp", "serve"]
    }
  }
}

Or if you installed Nastech in a specific location:

{
  "mcpServers": {
    "nastech": {
      "command": "/home/user/.nastech/nastech-agent/venv/bin/nastech",
      "args": ["mcp", "serve"]
    }
  }
}

Available tools

The MCP server exposes 10 tools, matching OpenClaw's channel bridge surface plus a Nastech-specific channel browser:

Tool	Description
`conversations_list`	List active messaging conversations. Filter by platform or search by name.
`conversation_get`	Get detailed info about one conversation by session key.
`messages_read`	Read recent message history for a conversation.
`attachments_fetch`	Extract non-text attachments (images, media) from a specific message.
`events_poll`	Poll for new conversation events since a cursor position.
`events_wait`	Long-poll / block until the next event arrives (near-real-time).
`messages_send`	Send a message through a platform (e.g. `telegram:123456`, `discord:#general`).
`channels_list`	List available messaging targets across all platforms.
`permissions_list_open`	List pending approval requests observed during this bridge session.
`permissions_respond`	Allow or deny a pending approval request.

Event system

The MCP server includes a live event bridge that polls Nastech's session database for new messages. This gives MCP clients near-real-time awareness of incoming conversations:

# Poll for new events (non-blocking)
events_poll(after_cursor=0)

# Wait for next event (blocks up to timeout)
events_wait(after_cursor=42, timeout_ms=30000)

Event types: message, approval_requested, approval_resolved

The event queue is in-memory and starts when the bridge connects. Older messages are available through messages_read.

Options

nastech mcp serve              # Normal mode
nastech mcp serve --verbose    # Debug logging on stderr

How it works

The MCP server reads conversation data directly from Nastech's session store — ~/.nastech/state.db is the primary source, with sessions.json kept only as a legacy fallback. A background thread polls the database for new messages and maintains an in-memory event queue. For sending messages, it uses the same internal send engine (tools/send_message_tool.py) that powers cron delivery and the nastech send CLI.

The gateway does NOT need to be running for read operations (listing conversations, reading history, polling events). It DOES need to be running for send operations, since the platform adapters need active connections.

Current limits

The embedded nastech mcp serve exposes a stdio-only MCP server today. If you need an HTTP MCP server, run a separate adapter — or, much more commonly, use the MCP client side of Nastech, which already speaks both stdio and HTTP (url + headers in mcp_servers.yaml / config.yaml; see HTTP servers above).
Event polling at ~200ms intervals via mtime-optimized DB polling (skips work when files are unchanged)
No claude/channel push notification protocol yet
Text-only sends (no media/attachment sending through messages_send)

What MCP gives you​

Quick start​

Catalog: one-click install for Nastech-approved MCPs​

Tool selection at install time​

Trust model​

Manifest version compatibility​

Runtime ${ENV_VAR} substitution​

Entries that need your own OAuth app (no DCR)​

Updating tool selection later​

Updating the catalog manifest​

Suggestion metadata (suggest:)​

Two kinds of MCP servers​

Stdio servers​

HTTP servers​

OAuth-authenticated HTTP servers​

mTLS / client certificates​

Per-user identity header​

Basic configuration reference​

Common keys​

Minimal stdio example​

Recycling memory-heavy stdio servers​

Minimal HTTP example​

Built-in presets​

How Nastech registers MCP tools​

Tool-result sanitization and _meta​

MCP utility tools​

Important​

Per-server filtering​

Disable a server entirely​

Whitelist server tools​

Blacklist server tools​

Glob patterns​

Precedence rule​

Filter utility tools too​

Full example​

What happens if everything is filtered out?​

Runtime behavior​

Discovery time​

Lazy start​

Dynamic Tool Discovery​

Reloading​

Toolsets​

Security model​

Stdio env filtering​

Config-level exposure control​

Example use cases​

GitHub server with a minimal issue-management surface​

Stripe server with dangerous actions removed​

Filesystem server for a single project root​

Troubleshooting​

MCP server not connecting​

Remote (HTTP) server rejects the connection​

Tools not appearing​

Why didn't resource or prompt utilities appear?​

Parallel Tool Calls​

MCP Sampling Support​

MCP Elicitation Support​

Running Nastech as an MCP server​

When to use this​

Quick start​

MCP client configuration​

Available tools​

Event system​

Options​

How it works​

Current limits​

Related docs​

What MCP gives you

Quick start

Catalog: one-click install for Nastech-approved MCPs

Tool selection at install time

Trust model

Manifest version compatibility

Runtime `${ENV_VAR}` substitution

Entries that need your own OAuth app (no DCR)

Updating tool selection later

Updating the catalog manifest

Suggestion metadata (`suggest:`)

Two kinds of MCP servers

Stdio servers

HTTP servers

OAuth-authenticated HTTP servers

mTLS / client certificates

Per-user identity header

Basic configuration reference

Common keys

Minimal stdio example

Recycling memory-heavy stdio servers

Minimal HTTP example

Built-in presets

How Nastech registers MCP tools

Tool-result sanitization and `_meta`

MCP utility tools

Important

Per-server filtering

Disable a server entirely

Whitelist server tools

Blacklist server tools

Glob patterns

Precedence rule

Filter utility tools too

Full example

What happens if everything is filtered out?

Runtime behavior

Discovery time

Lazy start

Dynamic Tool Discovery

Reloading

Toolsets

Security model

Stdio env filtering

Config-level exposure control

Example use cases

GitHub server with a minimal issue-management surface

Stripe server with dangerous actions removed

Filesystem server for a single project root

Troubleshooting

MCP server not connecting

Remote (HTTP) server rejects the connection

Tools not appearing

Why didn't resource or prompt utilities appear?

Parallel Tool Calls

MCP Sampling Support

MCP Elicitation Support

Running Nastech as an MCP server

When to use this

Quick start

MCP client configuration

Available tools

Event system

Options

How it works

Current limits

Related docs