What's Changed

• fix: documentation typos by @Artmorse in #608
• fix: prevent tools invocation without valid session initialization by @ezynda3 in #607
• fix: make transport Start() idempotent to resolve issue #583 by @ezynda3 in #606
• feat: extend resource middlewares to resource templates by @tjhop in #582
• Preserve Tool _meta when marshaling to JSON by @jaredly in #609
• fix: reuse sessions correctly in streamable HTTP transport by @ezynda3 in #615

New Contributors

• @Artmorse made their first contribution in #608
• @jaredly made their first contribution in #609

Full Changelog: v0.42.0-beta.1...v0.42.0-beta.2

What's Changed

• HTTP Sampling Improvements by @ezynda3 in #601
• feat: update type definition of _meta field to text/blob resources. by @rabbah in #591

New Contributors

• @rabbah made their first contribution in #591

Full Changelog: v0.41.1...v0.42.0-beta.1

What's Changed

• fix: replace bufio.Scanner with bufio.Reader to support large message… by @ezynda3 in #603

Full Changelog: v0.41.0...v0.41.1

What's Changed

• fix(oauth): use oauth-authorization-server discovery before default endpoints by @trungutt in #581
• Improve JSON-RPC error handling with typed errors and response constructors by @peteski22 in #595
• fix: Streamable HTTP client ping response handling by @havasik in #578
• feat: add support for call tool result annotations by @Crescent617 in #547

New Contributors

• @trungutt made their first contribution in #581
• @havasik made their first contribution in #578
• @Crescent617 made their first contribution in #547

Full Changelog: v0.40.0...v0.41.0

What's Changed

• feat(get-server-tools): add GetTools method for retrieve MCPServer.tools by @ValeriiStepanets in #437
• fix: don't share mutex between tools/resources by @tjhop in #574
• docs(server): Correct custom endpoint example for streamable HTTP transport by @IAmSurajBobade in #577
• feat: add NewToolResultJSON by @changkun in #550
• Do not panic on nil io by @sam-at-luther in #446
• Remove useless allocations; use (*Type)(nil) instead by @mikeschinkel in #545
• improve streamable http sse logging by @ethanoroshiba in #508
• feat!: add context.Context to TokenStore methods by @sd2k in #557
• Detect Pong from MCP Client and skip Session ID validation by @struckoff in #539
• feat: implement MCP elicitation support (#413) by @JBUinfo in #548

New Contributors

• @ValeriiStepanets made their first contribution in #437
• @IAmSurajBobade made their first contribution in #577
• @changkun made their first contribution in #550
• @sam-at-luther made their first contribution in #446
• @mikeschinkel made their first contribution in #545
• @ethanoroshiba made their first contribution in #508
• @struckoff made their first contribution in #539
• @JBUinfo made their first contribution in #548

Full Changelog: v0.39.1...v0.40.0

What's Changed

• fix(tool): Do not return empty outputSchema by @alex210501 in #573

Full Changelog: v0.39.0...v0.39.1

What's Changed

• fix: use bufio.Scanner for stdio transport to avoid panic when stdio mcp server outputs a long line by @WingT in #464
• fix(tool): Return the OutputSchema from the tool definition by @alex210501 in #571
• feat: add resource handler middleware capability by @tjhop in #569
• feat: add tls support for streamable-http by @opencow in #568
• fix: prevent double-starting stdio transport in client by @linw1995 in #564
• docs(client): improve server reliability and error handling by @appleboy in #560
• oauth client example: skip DCR if MCP_CLIENT_ID is set by @djoreilly in #549

New Contributors

• @WingT made their first contribution in #464
• @alex210501 made their first contribution in #571
• @tjhop made their first contribution in #569
• @opencow made their first contribution in #568
• @linw1995 made their first contribution in #564
• @appleboy made their first contribution in #560
• @djoreilly made their first contribution in #549

Full Changelog: v0.38.0...v0.39.0

What's Changed

• fix: resolve stdio transport race condition for concurrent tool calls by @ezynda3 in #529
• fix CallToolResult json marshaling and unmarshaling: need structuredC… by @sunfuze in #523
• feat: refactor constants for resource content types by @CocaineCong in #489
• feat: add missing SetPrompts, DeleteResources, and SetResources methods by @vasayxtx in #445
• feat: support creating tools using go-struct-style input schema by @Grivn in #534
• fix: remove duplicate methods server.SetPrompts & server.SetResources by @matthisholleville in #542

New Contributors

• @sunfuze made their first contribution in #523
• @Grivn made their first contribution in #534
• @matthisholleville made their first contribution in #542

Full Changelog: v0.37.0...v0.38.0

⚠️ Breaking Changes

The Result.Meta field type has changed from map[string]any to *Meta. Code that directly accesses or sets this field will need to be updated:

// Before (v0.36.0 and earlier):
result.Meta = map[string]any{"key": "value"}

// After (v0.37.0):
result.Meta = &mcp.Meta{AdditionalFields: map[string]any{"key": "value"}}

What's Changed

• Replace Prompts/Resources/Resource Templates by @dgageot in #518
• Update server.go race condition by @outofthisworld in #524
• task: add _meta field to relevant types as defined in MCP specification by @buraksenn in #429
• feat: implement sampling support for Streamable HTTP transport by @andig in #515
• Fix SSE transport not properly handling HTTP/2 NO_ERROR disconnections by @okoshi-f in #509
• feat: add thread-safe SetExpectedState for cross-request OAuth flows by @sd2k in #500
• feat: allow to set a custom logger in the SSE and STDIO clients by @caarlos0 in #525

New Contributors

• @outofthisworld made their first contribution in #524
• @buraksenn made their first contribution in #429
• @andig made their first contribution in #515
• @okoshi-f made their first contribution in #509
• @caarlos0 made their first contribution in #525

Full Changelog: v0.36.0...v0.37.0

What's Changed

• Add defs field to ToolsInputSchema by @ostafen in #488
• Remove sampling_server binary file by @JeffreyCA in #512
• chore: remove comments related to JSON-Batching by @cryo-zd in #514
• feat: support structured content and output schema by @pottekkat in #460
• Hide error log when it's not useful by @dgageot in #517

New Contributors

• @ostafen made their first contribution in #488
• @JeffreyCA made their first contribution in #512
• @dgageot made their first contribution in #517

Full Changelog: v0.35.0...v0.36.0