modelcontextprotocol/python-sdk

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The official Python SDK for Model Context Protocol servers and clients

Stars: 24.3k
Forks: 4k
Open beginner issues: 49
Indexed issues: 251
Avg merge: 1d 11h
Merged PRs (30d): 30

Dominant language: Python
License: MIT
Last GitHub push: Sep 16, 2026
Latest indexed: Sep 20, 2026
Contributing guide: Contributing guide
Code of conduct: Code of conduct
Beginner labels: good first issue help wanted

Beginner friendly Everything

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Streamable HTTP client logs a WARNING for valid 202 Accepted on session termination (DELETE) Open

v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 85/100

modelcontextprotocol/python-sdk#3546 · 5 comments · Opened Sep 19, 2026
Server ClientAuthenticator requires client_id in token body, rejecting valid client_secret_basic requests (RFC 6749 §2.3.1) Open

v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 76/100

modelcontextprotocol/python-sdk#3545 · 1 comment · Opened Sep 18, 2026
Revocation requires client_secret to be present Open

v1 v2

Difficulty 1/5 Under an hour Newbie friendliness 91/100

modelcontextprotocol/python-sdk#3508 · 2 comments · Opened Sep 15, 2026
Does same-origin redirect enforcement break MCP servers behind a reverse proxy? Open

Difficulty 2/5 1-3 hours Newbie friendliness 64/100

modelcontextprotocol/python-sdk#3504 · Opened Sep 15, 2026
Streamable HTTP stateless servers hang clients on the listen-mode GET (_handle_get_request opens a hold-open SSE stream) Open

v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 82/100

modelcontextprotocol/python-sdk#3492 · 1 comment · Opened Sep 11, 2026
pkg_version() in Server.create_initialization_options doesn't guard against importlib.metadata.version() returning None Open

v1

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

modelcontextprotocol/python-sdk#3487 · 3 comments · Opened Sep 9, 2026
Simplify `src/mcp/shared/metadata_utils.py::get_display_name` logic. Open

Difficulty 1/5 Under an hour Newbie friendliness 88/100

modelcontextprotocol/python-sdk#3480 · 1 comment · Opened Sep 8, 2026
[Bug] Client sends empty _meta:{} on every request; strict servers (Meta Ads MCP) reject with HTTP 400 Open

v2

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

modelcontextprotocol/python-sdk#3473 · 2 comments · Opened Sep 8, 2026
StreamableHTTP: a client disconnect while reading the POST body is logged as an exception and answered 500 Open

v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

modelcontextprotocol/python-sdk#3469 · 2 comments · Opened Sep 7, 2026
check_resource_allowed treats /api/../admin as under /api Open

v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 82/100

modelcontextprotocol/python-sdk#3464 · 3 comments · Opened Sep 6, 2026
DNS rebinding :* allowlist matches Host/Origin suffixes that are not ports Open

v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 84/100

modelcontextprotocol/python-sdk#3463 · 2 comments · Opened Sep 6, 2026
[v2] modern streamable HTTP watch_disconnect can busy-loop and peg a CPU core Open

v2

Difficulty 2/5 1-3 hours Newbie friendliness 86/100

modelcontextprotocol/python-sdk#3439 · 3 comments · Opened Sep 3, 2026
coerce_request_id() folds non-canonical numeric strings, conflating wire-distinct JSON-RPC ids Open

v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 84/100

modelcontextprotocol/python-sdk#3432 · 4 comments · Opened Sep 2, 2026
test_safe_join_rejects_symlink_escape fails on Windows without elevation or Developer Mode Open

v2

Difficulty 1/5 Under an hour Newbie friendliness 88/100

modelcontextprotocol/python-sdk#3408 · 3 comments · Opened Aug 28, 2026
OAuthClientProvider auth lock is permanently poisoned when httpx closes async_auth_flow from a different task (RuntimeError: The current task is not holding this lock) Open

v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 82/100

modelcontextprotocol/python-sdk#3382 · 4 comments · Opened Aug 25, 2026
pyjwt[crypto] as an unconditional dependency blocks installation on platforms without a cryptography wheel (e.g. Windows on ARM) Open

v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 75/100

modelcontextprotocol/python-sdk#3373 · 6 comments · Opened Aug 24, 2026
Client treats JSON-null structuredContent as missing, skipping outputSchema validation Open

spec-2026-07-28 v2

Difficulty 2/5 1-3 hours Newbie friendliness 75/100

modelcontextprotocol/python-sdk#3345 · 2 comments · Opened Aug 20, 2026
Prompt validation errors are logged with an unnecessary traceback Open

v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

modelcontextprotocol/python-sdk#3342 · 2 comments · Opened Aug 20, 2026
docs: no guidance for supporting SDK 1.x and 2.x at the same time Open

v2

Difficulty 2/5 Half a day Newbie friendliness 62/100

modelcontextprotocol/python-sdk#3309 · 10 comments · Opened Aug 14, 2026
Streamable HTTP clean EOF reconnects can exceed the request retry budget Open

bug needs confirmation P2 v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 88/100

modelcontextprotocol/python-sdk#3307 · 5 comments · Opened Aug 14, 2026
find_context_parameter treats a Context return annotation as a parameter Open

P3 v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

modelcontextprotocol/python-sdk#3298 · 5 comments · Opened Aug 12, 2026
resource_url_from_server_url preserves explicit default ports Open

P3 v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 76/100

modelcontextprotocol/python-sdk#3297 · 1 comment · Opened Aug 12, 2026
Expose create_mcp_http_client and McpHttpClientFactory as public API (2.0 made them private-only) Open

P1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

modelcontextprotocol/python-sdk#3238 · 4 comments · Opened Aug 3, 2026
Add `ClientSession.register_tool_schema()` for dynamic tool discovery patterns Open

enhancement needs decision P3 v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

modelcontextprotocol/python-sdk#3145 · 3 comments · Opened Jul 22, 2026
RequireAuthMiddleware omits RFC 6750 scope in WWW-Authenticate on 401/403 Open

auth bug needs confirmation P2 v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

modelcontextprotocol/python-sdk#3103 · 2 comments · 4 reactions · Opened Jul 16, 2026
FastMCP tool argument models silently ignore unknown/misspelled arguments (extra=ignore default) Open

enhancement needs decision P2 v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 76/100

modelcontextprotocol/python-sdk#3067 · 1 comment · 1 reaction · Opened Jul 6, 2026
FuncMetadata.pre_parse_json mis-detects str | None as non-string and corrupts JSON-looking string arguments Open

bug P2 v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

modelcontextprotocol/python-sdk#3055 · 2 comments · Opened Jul 2, 2026
WWW-Authenticate parsing matches a field name as a substring of another auth-param Open

auth bug P2 v2

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

modelcontextprotocol/python-sdk#3009 · 2 comments · Opened Jun 27, 2026
[Bug] check_capability does not validate elicitation sub-capabilities (form/url) Open

bug needs confirmation P2 v2

Difficulty 2/5 1-3 hours Newbie friendliness 82/100

modelcontextprotocol/python-sdk#2965 · 2 comments · Opened Jun 25, 2026
dict[str, T] tool return types lose Annotated/Field metadata in output schema Open

bug P3 v2

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

modelcontextprotocol/python-sdk#2935 · 2 comments · Opened Jun 20, 2026
`simple-auth` is not working as expected Open

auth bug P2

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

modelcontextprotocol/python-sdk#2826 · Opened Jun 10, 2026
OAuth handler doesn't support redirect URLs with params Open

auth bug P2

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

modelcontextprotocol/python-sdk#2776 · 2 comments · Opened Jun 3, 2026
streamable_http client does not send `Origin` header → rejected with 403 by spec-compliant servers (e.g. go-sdk `CrossOriginProtection`) Open

enhancement needs decision P3

Difficulty 2/5 1-3 hours Newbie friendliness 75/100

modelcontextprotocol/python-sdk#2727 · 3 comments · Opened May 30, 2026
`ClientSessionGroup` attempts to use capabilities that were not advertised Open

bug fix proposed P2 ready for work

Difficulty 2/5 1-3 hours Newbie friendliness 76/100

modelcontextprotocol/python-sdk#2689 · 3 comments · Opened May 26, 2026
Return 405 on GET when stateless_http=True Open

bug P2

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

modelcontextprotocol/python-sdk#2474 · 4 comments · 2 reactions · Opened Apr 19, 2026
Windows: TextIOWrapper in stdio_server() emits CRLF instead of LF, corrupting newline-delimited JSON messages Open

bug fix proposed P2 ready for work

Difficulty 1/5 Under an hour Newbie friendliness 88/100

modelcontextprotocol/python-sdk#2433 · 9 comments · Opened Apr 13, 2026
McpError is not pickle-safe and fails to unpickle Open

bug fix proposed P2 ready for work

Difficulty 2/5 1-3 hours Newbie friendliness 74/100

modelcontextprotocol/python-sdk#2431 · 9 comments · Opened Apr 13, 2026
StreamableHTTP client: _handle_reconnection resets attempt counter to 0, causing infinite retry loop Open

bug P2

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

modelcontextprotocol/python-sdk#2393 · 2 comments · Opened Apr 5, 2026
ClientSession: add public API for updating callbacks after initialization Open

enhancement needs decision P3

Difficulty 2/5 1-3 hours Newbie friendliness 70/100

modelcontextprotocol/python-sdk#2379 · 4 comments · Opened Mar 30, 2026
Don't override client_metadata.scopes if they are already set Open

auth enhancement needs decision P2

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

modelcontextprotocol/python-sdk#2317 · 5 comments · Opened Mar 20, 2026
Bug: validate_scope rejects client scopes when required scopes in None Open

auth bug P2 ready for work

Difficulty 2/5 1-3 hours Newbie friendliness 64/100

modelcontextprotocol/python-sdk#2216 · 5 comments · Opened Mar 5, 2026
Using transport="stdio" closes real stdio, causing ValueError after server exits Open

bug good first issue P3

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

modelcontextprotocol/python-sdk#1933 · 8 comments · Opened Jan 22, 2026
ClientAuthenticator ignores token_endpoint_auth_method="none" when client_secret is stored Open

auth bug needs confirmation needs decision P2

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

modelcontextprotocol/python-sdk#1842 · 6 comments · Opened Jan 8, 2026
More control over stderr in stdio client Open

enhancement needs decision P3

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

modelcontextprotocol/python-sdk#1806 · 1 comment · Opened Dec 19, 2025
ServerSession methods (create_message, elicit_form) don't expose progress_callback parameter Open

enhancement needs decision P2

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

modelcontextprotocol/python-sdk#1671 · 2 comments · Opened Nov 25, 2025
ClientDisconnect returns HTTP 500 Open

bug P2 ready for work

Difficulty 2/5 1-3 hours Newbie friendliness 76/100

modelcontextprotocol/python-sdk#1648 · 6 comments · 1 reaction · Opened Nov 20, 2025
Improve docs on how to use `instructions` on `InitializeResult` Open

documentation P1 ready for work

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

modelcontextprotocol/python-sdk#1464 · 4 comments · 1 reaction · Opened Oct 10, 2025
Don’t use shell=True in mcp dev subprocess on Windows (command injection risk) Open

bug fix proposed P1 ready for work

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

modelcontextprotocol/python-sdk#1257 · 3 comments · Opened Aug 10, 2025
[docs] How to run FastMCP with args or env vars? Open

documentation P2 ready for work

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

modelcontextprotocol/python-sdk#339 · 3 comments · 1 reaction · Opened Mar 21, 2025

modelcontextprotocol/python-sdk

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