MCP: pass protocol cancellation through to Sentry API requests

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
65/100
Issue type
Feature
Clarity
Clearly specified
Activity status
Active
Tech stack
typescript
Domain
tooling

Research direction

Start at handleToolCall in packages/mcp-core/src/server.ts (around line 410) and trace how the tool context is built, then follow how the API client is constructed from it. The reference behavior is the shared transport in @sentry/api (transport.ts, test/cancellation.test.ts), which already honors per-request signals and stops retry backoff. Thread extra.signal through the context and every API call including polling and retry waits, recognizing cancellation by signal.aborted/abort reason. Done when a new test cancels an in-flight call, asserts no further API requests, and concurrent calls still complete.

Written by the indexing model from the issue text.

Description

When an MCP client cancels a tool call, the work keeps running. handleToolCall in packages/mcp-core/src/server.ts only takes params, so the SDK's extra.signal never reaches the tool context, the API client or its polling and retry waits.

The transport side is already done in @sentry/api. Its shared transport, which MCP uses since getsentry/toolkit#1722, honors per-request signals and stops retry backoff on abort (transport.ts, covered by test/cancellation.test.ts, from getsentry/sentry-api-schema#105).

What's left:

  • Thread extra.signal from the tool handler into the invocation context and every API call the tool makes, including polling and retry waits.
  • Keep cancellation scoped to the one invocation, so concurrent calls on the same server keep running.
  • Recognize cancellation by signal.aborted and the abort reason, not only error.name === "AbortError", since MCP reasons can be strings.
  • Add a test that cancels an in-flight tool call and checks that no further API requests go out.

Split out of getsentry/sentry-api-schema#95.

via @BYK.

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View Session [Sentry]

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