TurboMCP

A ground-up Rust SDK for the Model Context Protocol — both halves of the protocol, server and client — with a macro-driven, zero-boilerplate surface and strict spec compliance as a feature.

Status: 4.0.0-alpha.5 — a prerelease for community testing. v4 is a from-scratch rewrite of TurboMCP; the stable line is 3.x. Edition 2024, MSRV 1.88. It interoperates with the official Rust, TypeScript, Python and Go SDKs in both directions, on both revisions, and both halves are scored against the official MCP conformance suite: 231 successful server assertions and 488 distinct successful client scenario/check pairs using pinned client fixture corrections, with zero failures, skips, or warnings. All three advertised revisions (2025-06-18, 2025-11-25, 2026-07-28) are dated and frozen; 2026-07-28 is generated from the released schema/2026-07-28/, not the RC. Found something broken or unergonomic? Please open an issue.

What you get

• One macro defines a server. #[server] over an impl block turns #[tool] / #[resource] / #[prompt] methods into a fully-wired MCP server. The macro generates schema derivation code; schema values are initialized once at runtime and cloned for callers, and the advertised capabilities are derived from which markers are present — they can't drift from the implementation.
• Three protocol revisions, one handler. The same server answers 2025-06-18, 2025-11-25, and 2026-07-28. Your handlers speak version-neutral types; the version-specific wire shapes are conversions, not signature changes — including dropping, per session, the fields a revision predates. Pin the set with #[server(protocols("2025-11-25", …))].
• Transports behind one builder. stdio (default), Streamable HTTP (axum), and WebSocket. MyServer.run_stdio(), or .into_server().layer(…).serve(Http::bind(addr)): one runtime wires sessions, DELETE and graceful shutdown, with or without middleware. WebSocket rides the HTTP endpoint as a route, behind the same guards.
• The client too. A typed Client runs the handshake, negotiates the version, and speaks the same neutral API — interoperating with the official Rust SDK (rmcp) in both directions.
• Production seams. OAuth 2.1 on both halves (resource-server bearer validation and the client auth-code + PKCE flow), identity-keyed rate limiting, OpenTelemetry tracing + metrics, progress/logging, subscriptions, response caching (SEP-2549), and bidirectional elicitation — each opt-in behind a feature flag.

How this relates to rmcp, the official Rust SDK

rmcp is the official SDK, maintained in the modelcontextprotocol organization. It is the reasonable default, and this project is tested against it — cross-SDK interop tests run in both directions, a TurboMCP client against an rmcp server and the reverse, on every change, alongside the same matrix over HTTP against the official TypeScript (v2), Python and Go SDKs.

TurboMCP's interoperability tests pin rmcp 3.2. TurboMCP serves three revisions (2025-06-18, 2025-11-25, 2026-07-28) using separate generated wire types and exhaustive conversions to a neutral handler API. It does not serve 2024-11-05 or 2025-03-26.