What's Changed

• feat: client-side support for SEP-1577 sampling with tools by @jlowin in #1722
• Fix JSON-RPC error response ID matching by @crondinini-ant in #1720
• Add streamable_http_client which accepts httpx.AsyncClient instead of httpx_client_factory by @Kludex in #1177
• fix: use correct python command name in test_stdio.py by @WOnder93 in #1782

New Contributors

• @WOnder93 made their first contribution in #1782

Full Changelog: v1.23.3...v1.24.0

What's Changed

• refactor(auth): remove unused _register_client method by @maxisbey in #1748
• feat: add workflow to comment on PRs when released by @felixweinberger in #1750
• fix: allow MIME type parameters in resource validation (RFC 2045) by @antonpk1 in #1755
• Skip empty SSE data to avoid parsing errors by @injusticescorpio in #1753
• chore: remove release-comment workflow by @maxisbey in #1758

New Contributors

• @antonpk1 made their first contribution in #1755
• @injusticescorpio made their first contribution in #1753

Full Changelog: v1.23.2...v1.23.3

What's Changed

• fix: add lifespan context manager to StreamableHTTP mounting examples by @TheMailmans in #1669
• fix: handle ClosedResourceError in StreamableHTTP message router by @Edison-A-N in #1384
• fix: skip priming events and close_sse_stream for old protocol versions by @felixweinberger in #1719

New Contributors

• @TheMailmans made their first contribution in #1669
• @Edison-A-N made their first contribution in #1384

Full Changelog: v1.23.1...v1.23.2

What's Changed

• chore: update LATEST_PROTOCOL_VERSION to 2025-11-25 by @felixweinberger in #1715

Full Changelog: v1.23.0...v1.23.1

Summary

This release brings us up to speed with the latest MCP spec 2025-11-25. Take a look at the latest spec as well as the release blog post.

What's Changed

• Add tests for JSON Schema 2020-12 field preservation (SEP-1613) by @felixweinberger in #1649
• Add client_secret_basic authentication support by @jonshea in #1334
• Implement SEP-1577 - Sampling With Tools by @ochafik in #1594
• SEP-1330: Elicitation Enum Schema Improvements and Standards Compliance by @chughtapan in #1246
• [auth][conformance] add conformance auth client by @pcarleton in #1640
• Implement SEP-986: Tool name validation by @felixweinberger in #1655
• fix: url for spec by @felixweinberger in #1659
• feat: implement SEP-991 URL-based client ID (CIMD) support by @pcarleton in #1652
• Update doc string on custom_route by @pcarleton in #1660
• Implement SEP-1036: URL mode elicitation for secure out-of-band interactions by @cbcoutinho in #1580
• Skip empty SSE data to avoid parsing errors by @felixweinberger in #1670
• SEP-1686: Tasks by @maxisbey in #1645
• Add on_session_created callback option by @crondinini-ant in #1710
• Add SSE polling support (SEP-1699) by @felixweinberger in #1654
• Support client_credentials flow with JWT and Basic auth by @pcarleton in #1663
• feat: backwards-compatible create_message overloads for SEP-1577 by @felixweinberger in #1713
• Auto-enable DNS rebinding protection for localhost servers by @pcarleton (d3a1841)

New Contributors

• @ochafik made their first contribution in #1594

Full Changelog: v1.22.0...v1.23.0

What's Changed

• feat: Pass through and expose additional parameters in ClientSessionGroup.call_tool and .connect_to_server by @inaku-Gyan in #1576
• chore: Lazy import jsonschema library by @wuliang229 in #1596
• docs: Update examples to use stateless HTTP with JSON responses by @domdomegg in #1499

New Contributors

• @wuliang229 made their first contribution in #1596

Full Changelog: v1.21.1...v1.22.0

Hotfix Release

This is a hotfix release to address a critical bug in OAuth scope handling that caused failures on 401 responses.

Related:

• #1630
• #1632

What's Changed

• fix get_client_metadata_scopes on 401 by @abliznyuk in #1631

New Contributors

• @abliznyuk made their first contribution in #1631

Full Changelog: v1.21.1...v1.21.2

What's Changed

• Add everything-server for comprehensive MCP conformance testing by @felixweinberger in #1587
• Get baseline 100% clean coverage by @maxisbey in #1553
• Add end-of-file-fixer pre-commit hook by @maxisbey in #1610
• Add coverage baseline commit to git-blame-ignore by @maxisbey in #1613
• Add SEP-1034 conformance test support to everything-server by @felixweinberger in #1604
• refactor: extract OAuth helper functions and simplify provider state by @maxisbey in #1586
• Add client_id_metadata_document_supported to OAuthMetadata by @maxisbey in #1603
• Fix OAuth discovery fallback and URL ordering by @maxisbey in #1624
• Refactor func_metadata() implementation by @Viicos in #1496
• Fix CI highest resolution test to actually test highest versions by @maxisbey in #1609

New Contributors

• @Viicos made their first contribution in #1496

Full Changelog: v1.21.0...v1.21.1

What's Changed

• docs: use article "an" before "MCP" instead of "a" by @koic in #1558
• Update Starlette to 0.49.1 in uv.lock by @ColeMurray in #1559
• Fix typo in ClientSessionGroup doc string by @inaku-Gyan in #1572
• Implement SEP-985: OAuth Protected Resource Metadata discovery fallback by @cbcoutinho in #1548
• Add --frozen flag to uv run commands in Claude config by @maxisbey in #1583
• Add get_server_capabilities() to ClientSession by @crondinini-ant in #1588

New Contributors

• @koic made their first contribution in #1558
• @ColeMurray made their first contribution in #1559
• @inaku-Gyan made their first contribution in #1572
• @cbcoutinho made their first contribution in #1548
• @crondinini-ant made their first contribution in #1588

Full Changelog: v1.20.0...v1.21.0