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loopctl

`src/mcp/convert.rs` — the MCP conversion layer [feature: mcp]

The mapping between loopctl types and MCP wire types, in both directions, with the safety validation on the way out.

Key items

  • Inbound: bridge_content(&ContentBlock) -> ToolContentPart (text, images, embedded resources as text notes — nothing silently dropped); bridge_result(...) -> ToolOutput (isError → is_error; structuredContent carried as a JSON-stringified text part; error with no content → McpError::EmptyToolError).
  • Outbound: tool_schema_to_mcp(schema, is_read_only) -> Option<McpTool> — the tool→name rename; validation: schema must compile under jsonschema with external references refused (RefusingRetriever — no IO during tools/list), and the root must be a typed object; anything else → None + warning (tool omitted).
  • dispatch_result_to_call_tool(...) — every tool outcome becomes a tool-level result (hard failures included).
  • not_found_error(requested, available) — the METHOD_NOT_FOUND payload.

Behavior notes

  • Read-only forwarding is consistent with the spec’s defaults: readOnlyHint: true plus destructiveHint: false; non-read-only gets no annotations at all.
  • The validation is the security boundary for served schemas — a $ref pointing at a URL or file path would make your server do IO mid-listing; it is refused instead.
  • MCP’s name convention (^[a-zA-Z0-9_-]{1,64}$) is the embedding’s responsibility — loopctl imposes no rules.

Deep dive: MCP.