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Invoke MCP tools through ARP as bounded candidates

Stub

This How-to is a stub. End-to-end MCP invocation is planned as “wrapper node types + selection-time policy”; the full implementation is not yet shipped.

Goal​

You will invoke an imported MCP tool via ARP in a bounded way: Selection produces a candidate set and policy filters what is allowed.

When to use this​

  • You want MCP tools, but with bounded action space and audit artifacts.
  • You want policy to control which tools can be used for which tasks.

Prerequisites​

  • MCP tools imported into Node Registry as NodeTypes
  • Selection Service configured and able to rank/filter
  • PDP configured for selection-time candidate filtering

Steps​

  1. Ensure MCP tools appear as NodeTypes in Node Registry.
  2. Call Selection with a subtask and get a bounded CandidateSet.
  3. Bind to one candidate and generate the tool input args.
  4. Execute via Atomic Executor wrapper node.

Verify​

  • Candidate sets include only allowed MCP tools (policy-filtered).
  • Tool calls produce durable artifacts and do not leak secrets.

Troubleshooting​

  • Candidate set empty → tools filtered by policy or missing inventory → inspect registry + PDP logs.
  • Tool invocation fails → debug the wrapper node directly.
  • Output is unsafe → treat outputs as untrusted; add evaluators/policy gates.

Cleanup / Rollback​

  • Deprecate the MCP tool node types.

Next steps​