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MCP - Model Context Protocol

The mcp module connects external MCP servers. Their tools become virtual Digitorn tools (naming like mcp_<server>__<tool>), not a fixed catalog of mcp.connect / mcp.call_tool agent actions.

PropertyValue
Module idmcp
Fixed agent toolsnone (dynamic)
Transportsstdio / SSE / HTTP (Go client)

Configure servers​

yaml
tools:
  modules:
    mcp:
      config:
        auto_install: false
        servers:
          filesystem:
            transport: stdio
            command: npx
            args: ["-y", "@modelcontextprotocol/server-filesystem", "/tmp"]
  capabilities:
    grant:
      - module: mcp

Hub catalog / OAuth flows exist in the daemon - prefer the live Hub install flow over hand-written server entries when one is available.

Remote servers (SSE / streamable HTTP)​

A server that already runs somewhere else - not something Digitorn spawns as a local process - connects over the network instead of stdio:

yaml
tools:
  modules:
    mcp:
      config:
        servers:
          hosted:
            transport: streamable_http   # or: sse
            url: "https://example.com/mcp"
            headers:
              Authorization: "Bearer {{secret.HOSTED_MCP_TOKEN}}"
            timeout: 30                  # seconds, default 30

command/args/env only apply to stdio (they spawn the process); url/headers only apply to sse/streamable_http (there's nothing to spawn). Pick streamable_http unless the server specifically documents itself as SSE-only - it's the newer of the two wire formats. headers is a plain map, most often used for a bearer token the same way any other secret is referenced ({{secret.X}}).

For a server that needs a real OAuth exchange rather than a static bearer token, an inline auth: block (type, client_id, client_secret, scopes, authorize_url, token_url, pkce, ...) exists for advanced cases, but prefer the Hub's managed OAuth install flow first - it's what the install howto covers, and it avoids hand-rolling a token refresh cycle in your own app.

How agents call MCP tools​

Once connected, tools appear in the tool index like any other module action (subject to injection mode and grants). Use search_tools / get_tool / direct call / execute_tool.

Resources and prompts may be exposed as additional virtual tools when the server advertises them.