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McpError raised in tool handlers is swallowed as isError:true instead of propagating as JSON-RPC error

Status: Open.

#2770 In modelcontextprotocol/python-sdk;

· mengyunxie opened on Jun 2, 2026

Deep JSON-RPC request over stdio logs a validation error and leaves the original request pending

Status: Open.

#2751 In modelcontextprotocol/python-sdk;

· cclabadmin opened on Jun 1, 2026

Stateful Streamable HTTP: in-session exceptions are masked as an empty -32603; real cause only in a separate "Session crashed" log

Status: Open.

#2741 In modelcontextprotocol/python-sdk;

· SingingOwl opened on May 31, 2026

Proposal: Bridge for CLI‑first MCP servers (like typer-mcp)

Status: Open.

#2740 In modelcontextprotocol/python-sdk;

· Darussalamnoor opened on May 31, 2026

streamable_http client does not send Origin header → rejected with 403 by spec-compliant servers (e.g. go-sdk CrossOriginProtection)

enhancementRequest for a new feature that's not currently supportedRequest for a new feature that's not currently supported

needs decisionIssue is actionable, needs maintainer decision on whether to implementIssue is actionable, needs maintainer decision on whether to implement

P3Nice to haves, rare edge casesNice to haves, rare edge cases

Status: Open.

#2727 In modelcontextprotocol/python-sdk;

· fede-kamel opened on May 30, 2026

SEP-2243: Send required Mcp-Method/Mcp-Name HTTP headers

enhancementRequest for a new feature that's not currently supportedRequest for a new feature that's not currently supported

needs decisionIssue is actionable, needs maintainer decision on whether to implementIssue is actionable, needs maintainer decision on whether to implement

P1Significant bug affecting many users, highly requested featureSignificant bug affecting many users, highly requested feature

Status: Open.

#2715 In modelcontextprotocol/python-sdk;

· caomengxuan666 opened on May 29, 2026

streamable_http: early response.aclose() poisons keepalive connection, causes ~260ms latency on every subsequent tool call

bugSomething isn't workingSomething isn't working

needs reproneeds additional information to be able to reproduce bugneeds additional information to be able to reproduce bug

Status: Open.

#2707 In modelcontextprotocol/python-sdk;

· whocareyw opened on May 28, 2026

Flaky streamable-HTTP/SSE tests: TOCTOU port race under pytest -n auto

bugSomething isn't workingSomething isn't working

fix proposedBot has a verified fix diff in the commentBot has a verified fix diff in the comment

P2Moderate issues affecting some users, edge cases, potentially valuable featureModerate issues affecting some users, edge cases, potentially valuable feature

ready for workEnough information for someone to start working onEnough information for someone to start working on

Status: Open.

#2704 In modelcontextprotocol/python-sdk;

· Ar-maan05 opened on May 28, 2026

FastMCP: streamable_http_app() silently breaks when BaseHTTPMiddleware is added

potentially closeBot recommends closing — needs maintainer reviewBot recommends closing — needs maintainer review

Status: Open.

#2702 In modelcontextprotocol/python-sdk;

· hognek opened on May 27, 2026

Dead code path in MCPServer._handle_call_tool and incorrect call_tool return type

bugSomething isn't workingSomething isn't working

P3Nice to haves, rare edge casesNice to haves, rare edge cases

ready for workEnough information for someone to start working onEnough information for someone to start working on

v2Ideas, requests and plans for v2 of the SDK which will incorporate major changes and fixesIdeas, requests and plans for v2 of the SDK which will incorporate major changes and fixes

Status: Open.

#2695 In modelcontextprotocol/python-sdk;

· SHAI-Akshay-Tripathi opened on May 26, 2026

ClientSessionGroup attempts to use capabilities that were not advertised

bugSomething isn't workingSomething isn't working

fix proposedBot has a verified fix diff in the commentBot has a verified fix diff in the comment

P2Moderate issues affecting some users, edge cases, potentially valuable featureModerate issues affecting some users, edge cases, potentially valuable feature

ready for workEnough information for someone to start working onEnough information for someone to start working on

Status: Open.

#2689 In modelcontextprotocol/python-sdk;

· mr-brobot opened on May 26, 2026

OAuthClientInformationFull.redirect_uris: pydantic strict-type-equality breaks AnyUrl(x) != AnyHttpUrl(x) round-trip

authIssues and PRs related to Authentication / OAuthIssues and PRs related to Authentication / OAuth

bugSomething isn't workingSomething isn't working

fix proposedBot has a verified fix diff in the commentBot has a verified fix diff in the comment

P2Moderate issues affecting some users, edge cases, potentially valuable featureModerate issues affecting some users, edge cases, potentially valuable feature

ready for workEnough information for someone to start working onEnough information for someone to start working on

Status: Open.

#2687 In modelcontextprotocol/python-sdk;

· ptrhrsch-arch opened on May 26, 2026