---
id: adapter-mcp
name: from_mcp + to_mcp (mcp feature)
status: pending
depends_on: [client-http-host, gateway-routes]
scope: broad
risk: medium
impact: component
level: implementation
tags: [adapters, mcp, phase-3]
---

## Description

Port both MCP adapters from
`/workspace/@alkdev/alknet/crates/alknet-http/src/adapters/{from_mcp/`,
`to_mcp.rs}` behind the `mcp` feature (rmcp, streamable HTTP only —
ADR-037). from_mcp: tools/list discovery, per-tool HandlerRegistration
(Mutation, HandlerKind::Once, FromMCP leaf), structuredContent-preferred
output handling, ContentBlock-union fallback, isError→CallError.
to_mcp: 4 fixed gateway tools (search/schema/call/batch — Sub AND Pub
excluded), StreamableHttpService into axum under /mcp with bearer
middleware. Shared dispatch spine with to_openapi via GatewayDispatch.

## Acceptance Criteria

- [ ] Both adapters behind `mcp`; default features compile without rmcp
- [ ] from_mcp round-trip against a mock MCP server (tools/list, tools/call, structured + content-block outputs)
- [ ] to_mcp: 4 tools listed; call dispatch filtered by ACL; Pub/Sub ops excluded
- [ ] stdio transport not present anywhere (dependency audit)
- [ ] `cargo test --all-features` passes

## References

- docs/architecture/http-mcp.md
- docs/architecture/decisions/037-mcp-stdio-transport-exclusion.md, 041-mcp-tool-gateway-pattern.md
- Old source: `/workspace/@alkdev/alknet/crates/alknet-http/src/adapters/from_mcp/`, `to_mcp.rs`, `tests/from_mcp_integration.rs`

## Notes

> Agent fills during implementation.

## Summary

> Agent fills on completion.