No default timeout for requests (unlike TS SDK)

[ochafik]

Initial Checks

• I confirm that I'm using the latest version of MCP Python SDK
• I confirm that I searched for my issue in https://github.com/modelcontextprotocol/python-sdk/issues before opening this issue

Description

Spec states: Implementations SHOULD establish timeouts for all sent requests, to prevent hung connections and resource exhaustion.

The TypeScript SDK does have a default timeout of 60 seconds on requests, and the difference between Python & TypeScript is the crux of modelcontextprotocol/typescript-sdk#245 (which also suggests 60 seconds might not be long enough). Also related, TypeScript has a resetTimeoutOnProgress option (defaulting to falst), which would probably be useful if we do introduce a default to the Python SDK.

Example Code

Python & MCP Python SDK

Latest

[felixweinberger]

#1159 adds timeout support

[dgenio]

Thanks for opening this — having sensible timeout behavior is critical for production MCP usage, especially when LLMs are orchestrating many tool calls.

From a broader SDK perspective, there are two related gaps:

1. Server-side tool timeouts

   • Tool and resource handlers are awaited without any server-side timeout wrapper (e.g. anyio.fail_after()).
   • A single hung tool can effectively stall a session unless the client enforces its own timeout and tears down the connection.
   • For typical GenAI workflows, agents often retry or fan out tool calls, so one hung tool can easily multiply into many hung requests.

2. Retry policy surfaced to clients

   • On the client side, we currently have read_timeout_seconds but no higher-level RetryPolicy abstraction that distinguishes between:
     • transient errors (network, transport issues),
     • server-side timeouts,
     • non-retryable errors (validation, permission, etc.).
   • Without a structured view of error types, LLM agents end up guessing when to retry.

Concretely, it might be useful to extend this issue (or create a follow-up) to cover:

• A configurable server-side timeout for tool execution (with a reasonable default, e.g. 30s), returning a clear “timeout” error on the protocol layer.
• A client-side RetryPolicy or equivalent hook that:
  • treats timeouts and transient transport issues as retryable (with backoff),
  • treats validation/semantic errors as non-retryable by default.

If maintainers are open to this direction, I’d be happy to help draft a more detailed proposal and/or work on a PR that wires in:

• a per-tool execution timeout on the server, and
• a minimal RetryPolicy on the client with a simple backoff strategy and clear error messages.

[maxisbey]

This is a valid gap - we should match the TypeScript SDK's behavior here.

What the spec says:

"Implementations SHOULD establish timeouts for all sent requests, to prevent hung connections and resource exhaustion. When the request has not received a success or error response within the timeout period, the sender SHOULD issue a cancellation notification for that request and stop waiting for a response."

This is specifically about client-side request timeouts - how long the client waits for a response from the server.

TypeScript SDK:

• Default DEFAULT_REQUEST_TIMEOUT_MSEC = 60000 (60 seconds)
• Per-request timeout option
• resetTimeoutOnProgress option

Python SDK currently:

• Has read_timeout_seconds and request_read_timeout_seconds but no default
• No resetTimeoutOnProgress equivalent

Proposed fix:
Add a default timeout of 60 seconds to match TS SDK, with the ability to override per-request. Could also add progress-based timeout reset as a follow-up.

_{AI Disclaimer}

[dgenio]

Hi — I'm the author of PR #1685 which aimed to address this issue with a server-side tool execution timeout.

That PR is now stale due to the fastmcp → mcpserver restructuring, and the REQUEST_TIMEOUT constant (-32001) has already been merged upstream separately.

Is there still interest in adding a configurable server-side tool execution timeout? If so, I'm happy to open a fresh PR against the current codebase. A couple of open questions:

1. Default timeout value — my PR used 300s (5 min), but the TypeScript SDK uses 60s. What's the preferred default?
2. Scope — should this only cover tool execution, or should it be a broader request-level timeout on the server side?

Would appreciate guidance before investing time in a rewrite.