codex-in-claude: Skill for Claude Code

Agent-Friendly MCP

Use this skill to make MCP servers easy for agents to discover, invoke correctly, recover from, and use at low token cost without sacrificing correctness.

Spec Baseline

This skill is written against the MCP 2026-07-28 specification (final, released 2026-07-28); the field names, capability paths, method set, and task lifecycle it uses follow that revision, including the io.modelcontextprotocol/tasks extension (SEP-2663). Status caveat: the 2026-07-28 changelog calls tasks an official extension while the ext-tasks specification repository still labels itself experimental — treat the task contract as extension-versioned and re-verify it against the extension spec when it cuts a release. The protocol core is stateless: there is no initialize handshake or session id — every request carries io.modelcontextprotocol/protocolVersion and io.modelcontextprotocol/clientCapabilities in _meta (both required), and servers advertise their own capabilities via the mandatory server/discover method. Server-initiated requests are gone: elicitation, sampling, and roots requests ride Multi Round-Trip Requests (resultType: "input_required" with inputRequests, answered by retrying with inputResponses), and subscription notifications — list-changed, resource-updated, and task notifications — ride an opt-in subscriptions/listen stream, while request-scoped notifications (notifications/progress, notifications/message) stay on the originating request's response stream. Every result carries a required resultType, and server/discover, list, and read results carry the native cache hints ttlMs and cacheScope on their resultType: "complete" results — MRTR interim results are never cacheable. Roots, sampling, logging, the HTTP+SSE transport, and Dynamic Client Registration are deprecated on a twelve-month minimum window; design new servers without them. The extensions framework is formal but demanding: an extension needs a reverse-DNS identifier, its own maintained specification, and negotiation by both peers (declared in clientCapabilities.extensions and server/discover), so a namespaced _meta key remains a private convention until someone does that work. This section is the single home for revision-level facts: which revision is baseline, its release status, the tasks-extension caveat, and what is deprecated or removed. Checklist rules and native-wire-shapes.md necessarily restate the mechanics they govern, including a governed surface's deprecation status; for the revision-level frame they cite this section rather than restating it. For clients that still speak 2025-11-25, the binding rules here still govern what you build; the old revision's wire differences and version-bound failure modes are cataloged in the informative mcp-2025-11-25-compat.md, and decisions/001-mcp-2026-07-28-rebase.md records the rebase decision, verified fact sheet, and impact matrix.