Issues

• A tool returning an empty list produces a CallToolResult with zero content blocks

  enhancementneeds decisionP2v1v2
  modelcontextprotocol/python-sdk#3305 · Filter by author hchittanuru3 opened on Aug 13, 2026
  1

• Add ClientSession.register_tool_schema() for dynamic tool discovery patterns

  enhancementneeds decisionP3v1v2
  modelcontextprotocol/python-sdk#3145 · Filter by author steditt opened on Jul 22, 2026
  4

• perf: JSONRPCMessage smart union scores all four branches on every inbound message

  enhancementneeds decisionP3v1v2
  modelcontextprotocol/python-sdk#3136 · Filter by author sandole opened on Jul 19, 2026

• Heavy sync init work (e.g. local ML models) starves stdio initialize/tool calls even with threadpool offload -- Windows GIL contention

  documentationenhancementneeds decisionP3v1v2
  modelcontextprotocol/python-sdk#3089 · Filter by author scotthibbs opened on Jul 12, 2026
  4

• FastMCP tool argument models silently ignore unknown/misspelled arguments (extra=ignore default)

  enhancementneeds decisionP2v1v2
  modelcontextprotocol/python-sdk#3067 · Filter by author ramonahl opened on Jul 6, 2026
  1

• Capabilities API + server/discover handler

  enhancementP2spec-2026-07-28v2
  modelcontextprotocol/python-sdk#2896 · Filter by author maxisbey opened on Jun 17, 2026 · 2026-07-28 spec support
  

• Implement SEP-2663: Tasks Extension

  enhancement
  modelcontextprotocol/python-sdk#2806 · Filter by author localden opened on Jun 6, 2026
  11

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

  enhancementneeds decisionP3
  modelcontextprotocol/python-sdk#2727 · Filter by author fede-kamel opened on May 30, 2026
  3

• ClientSession receive loop swallows callback exceptions, replying "Invalid request parameters" to the server instead of propagating to the call_tool awaiter

  enhancementneeds decisionP3
  modelcontextprotocol/python-sdk#2673 · Filter by author danielgshea opened on May 24, 2026
  4

• Add option to skip output validation for mcp client

  enhancementneeds decisionP3
  modelcontextprotocol/python-sdk#2626 · Filter by author germanbecker opened on May 17, 2026
  3

• ClientConfig has inconsistent naming: message_handler should be message_callback

  enhancementneeds decisionP3v2
  modelcontextprotocol/python-sdk#2588 · Filter by author fuyu-quant opened on May 13, 2026
  1

• Expose schema_generator on FastMCP for tool params schema generation

  enhancementneeds decisionP3
  modelcontextprotocol/python-sdk#2582 · Filter by author leowonglaw opened on May 13, 2026

• Add list_all_* helpers to drain pagination

  enhancementP3v2
  modelcontextprotocol/python-sdk#2556 · Filter by author CJGjr opened on May 8, 2026
  3

• Split the core from the server and client implementations

  enhancementneeds decisionP3v2
  modelcontextprotocol/python-sdk#2486 · Filter by author leiserfg opened on Apr 21, 2026
  4

• Specific ToolNotFoundError for easier handling than ToolError in multi-tenant environments

  enhancementneeds decisionP3
  modelcontextprotocol/python-sdk#2422 · Filter by author DevonFulcher opened on Apr 10, 2026
  4

• Inline $ref in tool inputSchema for LLM consumption (parity with typescript-sdk)

  enhancementneeds decisionP2
  modelcontextprotocol/python-sdk#2384 · Filter by author felixweinberger opened on Apr 2, 2026
  2

• ClientSession: add public API for updating callbacks after initialization

  enhancementneeds decisionP3
  modelcontextprotocol/python-sdk#2379 · Filter by author dgenio opened on Mar 30, 2026
  4

• Design: future of dependencies parameter on MCPServer

  enhancementneeds decisionP2v2
  modelcontextprotocol/python-sdk#2354 · Filter by author maxisbey opened on Mar 26, 2026
  2

• Add remove_prompt() and remove_resource() for parity with remove_tool()

  enhancementneeds decisionP3
  modelcontextprotocol/python-sdk#2331 · Filter by author rgoldstein1989 opened on Mar 22, 2026
  4

• Improve log clarity for "Terminating session: None" in stateless mode

  enhancementP3
  modelcontextprotocol/python-sdk#2329 · Filter by author kingpanther13 opened on Mar 22, 2026
  1

• Don't override client_metadata.scopes if they are already set

  authenhancementneeds decisionP2
  modelcontextprotocol/python-sdk#2317 · Filter by author artdent opened on Mar 20, 2026
  5

• pywin32 installation fails on Windows — hard dep only needed for client stdio, but pulled in for all users via eager import in __init__.py

  enhancementneeds decisionP2
  modelcontextprotocol/python-sdk#2233 · Filter by author sergeykad opened on Mar 6, 2026
  3

• Type the MCPServer handler pipeline: tool/resource/prompt return types

  enhancementv2
  modelcontextprotocol/python-sdk#2202 · Filter by author maxisbey opened on Mar 2, 2026

• MCPServer handlers should raise exceptions, not return error objects

  enhancementv2
  modelcontextprotocol/python-sdk#2153 · Filter by author maxisbey opened on Feb 27, 2026

• Add wildcard pattern support for allowed_hosts in transport security

  enhancementneeds confirmation
  modelcontextprotocol/python-sdk#2141 · Filter by author enkidulan opened on Feb 25, 2026
  2