modelcontextprotocol

modelcontextprotocol/python-sdk

The official Python SDK for Model Context Protocol servers and clients

Stars: 24.3k
Forks: 4k
Open beginner issues: 17
Indexed issues: 241
Avg merge: 1d 1h
Merged PRs (30d): 31

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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241 open issues indexed

How can I manage resource across multiple tool calls during one session? Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

modelcontextprotocol/python-sdk#3549 · Opened Sep 20, 2026
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 · 4 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
tests/client/test_client.py: 14 failures on Windows — AttributeError: '...Result' object has no attribute '_meta' Open

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

modelcontextprotocol/python-sdk#3544 · 1 comment · Opened Sep 18, 2026
OAuth client sends discovery/registration requests with no User-Agent, so WAF-fronted servers (Cloudflare) 403 the whole flow Open

v1 v2

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

modelcontextprotocol/python-sdk#3531 · 1 comment · Opened Sep 18, 2026
A resource template with a non-ASCII or space literal is advertised but can never be read Open

v1 v2

Difficulty 3/5 1-2 days Newbie friendliness 45/100

modelcontextprotocol/python-sdk#3526 · 1 comment · Opened Sep 18, 2026
Streamable HTTP client stays closed after an interrupted response and raises ExceptionGroup on cleanup Open

v1 v2

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

modelcontextprotocol/python-sdk#3522 · 1 comment · Opened Sep 17, 2026
A tool with a *args or **kwargs parameter is registered with a schema it can never satisfy Open

v1 v2

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

modelcontextprotocol/python-sdk#3514 · 1 comment · Opened Sep 16, 2026
ClientSession.call_tool issues a tools/list after every tools/call when the output-schema cache is empty — no opt-out; doubles round-trips on per-call sessions Open

v1 v2

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

modelcontextprotocol/python-sdk#3513 · 1 comment · Opened Sep 16, 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
OAuth client: authorization URL is built with a second `?` when the advertised `authorization_endpoint` already carries a query (RFC 6749 §3.1) Open

v1 v2

Difficulty 2/5 1-3 hours Newbie friendliness 35/100

modelcontextprotocol/python-sdk#3505 · 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 client: the standalone GET stream advertises Accept: application/json but can only read text/event-stream, then gives up silently Open

v1 v2

Difficulty 3/5 1-2 days Newbie friendliness 73/100

modelcontextprotocol/python-sdk#3503 · 1 comment · Opened Sep 14, 2026
Streamable HTTP: ASGI application returns before the full SSE body is sent Open

v1 v2

Difficulty 4/5 3-5 days Newbie friendliness 50/100

modelcontextprotocol/python-sdk#3494 · 2 comments · Opened Sep 11, 2026
MCPServer serves subscriptions/listen and advertises listChanged=true unconditionally — hold-open streams pin serverless invocations to the platform timeout Open

spec-2026-07-28 v2

Difficulty 4/5 3-5 days Newbie friendliness 57/100

modelcontextprotocol/python-sdk#3493 · 3 comments · Opened Sep 11, 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
ClientSessionGroup: a rejected connect_to_server leaves its transport running — the session is established before its components are validated Open

v1 v2

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

modelcontextprotocol/python-sdk#3490 · 2 comments · Opened Sep 10, 2026
Is one-auth-configuration-per-server a deliberate constraint? Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

modelcontextprotocol/python-sdk#3488 · Opened Sep 9, 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
Add SEP-2640 (Skills Extension) protocol support Open

modelcontextprotocol/python-sdk#3486 · 2 reactions · 1 assignee · Opened Sep 9, 2026
MCPServer has no x-mcp-header declaration mechanism and never validates one, so an invalid annotation is served happily and dropped by every client Open

spec-2026-07-28 v2

Difficulty 4/5 3-5 days Newbie friendliness 55/100

modelcontextprotocol/python-sdk#3484 · 3 comments · Opened Sep 9, 2026
Client never retries after -32020 HeaderMismatch, and there is no public way to pre-load the x-mcp-header map (SEP-2243 client SHOULD/MAY both unimplemented) Open

spec-2026-07-28 v2

Difficulty 4/5 3-5 days Newbie friendliness 52/100

modelcontextprotocol/python-sdk#3483 · 2 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
Missing prompt-level _meta support in MCPServer.prompt() and Prompt model Open

v1 v2

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

modelcontextprotocol/python-sdk#3476 · 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
[v2] Add an end-to-end public-client PKCE server contract Open

v1 v2

Difficulty 4/5 3-5 days Newbie friendliness 50/100

modelcontextprotocol/python-sdk#3472 · 1 comment · Opened Sep 8, 2026
# TypeScript npm install @modelcontextprotocol/sdk zod # Python pip install mcp Open

Difficulty 2/5 1-3 hours Newbie friendliness 30/100

modelcontextprotocol/python-sdk#3471 · 1 comment · 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
CallToolResult structuredContent is not alias-normalized to match outputSchema Open

v1 v2

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

modelcontextprotocol/python-sdk#3467 · 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
StdioServerParameters exposes no preexec_fn / rlimit / process-group hook for spawned MCP server subprocess Open

Difficulty 4/5 3-5 days Newbie friendliness 52/100

modelcontextprotocol/python-sdk#3457 · 4 comments · Opened Sep 6, 2026
1.x: streamable_http client leaves a request unresolved when the SSE response stream ends without a response (fixed on 2.x by #3047 — backport request for v1.x) Open

v1

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

modelcontextprotocol/python-sdk#3441 · 1 comment · Opened Sep 4, 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
TransportSecuritySettings.allowed_hosts is compared case-sensitively (NOT RFC 9110 compliant), so an uppercase host entry (the Windows default) rejects every fetch-based client with 421 Open

v1 v2

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

modelcontextprotocol/python-sdk#3437 · 5 comments · Opened Sep 3, 2026
In-process callback failures break tool calls and notification sends Open

v2

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

modelcontextprotocol/python-sdk#3434 · 1 comment · 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
Tool input schemas carry a pydantic-derived title on every property Open

v1 v2

Difficulty 3/5 1-2 days Newbie friendliness 52/100

modelcontextprotocol/python-sdk#3391 · 5 comments · Opened Aug 25, 2026
[v2] Expose request cancellation on MCPServer tool Context Open

v2

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

modelcontextprotocol/python-sdk#3389 · 1 comment · Opened Aug 25, 2026
A tool returning a non-finite float puts invalid JSON in the text content block Open

v1 v2

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

modelcontextprotocol/python-sdk#3385 · 1 comment · Opened Aug 25, 2026
ClientSessionGroup raises KeyError when a server exposes no tools, resources or prompts Open

v1 v2

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

modelcontextprotocol/python-sdk#3384 · 2 comments · Opened Aug 25, 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 SSRF / protocol confusion: streamable HTTP transport follows server 3xx into internal+loopback services (follow_redirects=True, no host validation; #2106 closed but fix #2180 never merged) Open

v1 v2

Difficulty 4/5 3-5 days Newbie friendliness 55/100

modelcontextprotocol/python-sdk#3358 · 6 comments · Opened Aug 21, 2026
[v2] Allow MCPServer to disable subscriptions/listen Open

spec-2026-07-28 v2

Difficulty 4/5 3-5 days Newbie friendliness 68/100

modelcontextprotocol/python-sdk#3357 · 5 comments · 4 reactions · Opened Aug 21, 2026
Server.call_tool()'s input-validation error result discards jsonschema.ValidationError's structured fields, leaving only free-text prose Open

v1 v2

Difficulty 3/5 1-2 days Newbie friendliness 55/100

modelcontextprotocol/python-sdk#3351 · 1 comment · Opened Aug 21, 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
A tool returning a non-finite float fails on the client with an error naming the tool Open

v1 v2

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

modelcontextprotocol/python-sdk#3341 · 2 comments · Opened Aug 20, 2026

A short digest of beginner-friendly GitHub issues.