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The Model Context Protocol ecosystem, verified

Current spec 2026-07-28

governance ·

Rust SDK promoted to Tier 1, joining TypeScript, Python, C# and Go

The Model Context Protocol project merged the Rust SDK's promotion from Tier 2 to Tier 1 in the official SDK listing on 2026-08-21, citing independent re-verification with the conformance suite: 67/67 server checks and 50/50 client checks against the frozen 2025-11-25 and 2026-07-28 requirement sets. Tier 1 now comprises TypeScript, Python, C#, Go and Rust; Ruby's own promotion proposal remains open.

The Model Context Protocol project promoted its Rust SDK from Tier 2 to Tier 1 in the official SDK listing on 2026-08-21, for both the current 2026-07-28 specification and the draft. The change was merged in PR #3287 against the Tier 1 assessment opened in issue #3179 on 2026-07-31.

The promotion record is specific about what Tier 1 required. The PR body cites an independent re-verification of the SDK at commit 1cf6deb using the project's conformance suite (0.2.0-alpha.11) against the frozen requirement sets for both 2025-11-25 and 2026-07-28: 67 of 67 server checks, 50 of 50 client checks, and 12 of 12 labels, alongside a stable rmcp 3.0.1 crate, same-day spec tracking, and published VERSIONING, DEPENDENCY_POLICY and ROADMAP documents.

Tier 1 now comprises five SDKs: TypeScript, Python, C#, Go and Rust. Java and Ruby remain at Tier 2, with Ruby's own Tier 1 promotion proposal (PR #3248, opened alongside its 1.2.0 release) still open - the Rust SDK cleared the bar first. The rmcp crate at the center of the promotion is the same one that shipped 3.1.4 on 2026-08-20 with 32-byte signing-key enforcement for MRTR request state.

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How was this verified, and what are the sources?

Published · confidence 0.97.

  1. Spec repo PR #3287 "Promote Rust SDK to Tier 1 in the SDK listing", merged 2026-08-21T12:30:14Z - moves the Rust SDK row from Tier 2 to Tier 1 in docs/docs/2026-07-28/sdk.mdx and docs/docs/draft/sdk.mdx; the PR body records independent re-verification at commit 1cf6deb with @modelcontextprotocol/conformance 0.2.0-alpha.11 against the frozen 2025-11-25 and 2026-07-28 requirement sets, server conformance 67/67, client conformance 50/50, 12/12 labels, stable rmcp 3.0.1, same-day spec tracking, and VERSIONING / DEPENDENCY_POLICY / ROADMAP published - accessed
  2. Issue #3179 "Rust SDK - Tier 1 Assessment", opened 2026-07-31, closed with the promotion - the Tier 1 application the PR cites - accessed
  3. PR #3287 file diff - shows the Rust row gaining the Tier 1 badge alongside TypeScript, Python, C# and Go, with Java and Ruby remaining Tier 2 and Swift and PHP at Tier 3 - accessed

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