The intent is reasonable (60s is too short for many agent operations), but the implementation has several issues:

1. No tests

This modifies a core constant that affects every request() call across the SDK. Zero new tests. At minimum, tests should cover: valid numeric string, empty string, non-numeric string ("abc"), negative number, zero, and the fallback when process.env is undefined (non-Node runtimes).

2. Environment variable name

MCP_TOOL_CALL_MCP_REQUEST_TIMEOUT_MSEC contains "MCP" twice and "TOOL_CALL" despite applying to all requests, not just tool calls. The constant is DEFAULT_REQUEST_TIMEOUT_MSEC. Suggested: MCP_REQUEST_TIMEOUT_MSEC (shorter, accurate scope).

3. Unnecessary try/catch

Number.parseInt() never throws. Number.parseInt(undefined) returns NaN, Number.parseInt("abc") returns NaN, and NaN > 0 is false. The try/catch is dead code. The > 0 check handles all invalid inputs correctly on its own.

4. process.env assumes Node.js

The MCP SDK runs in Cloudflare Workers, Deno, and browser-like environments where process.env may not exist. The try/catch accidentally guards against this (catching the ReferenceError), but this should be an intentional check:

const envValue = typeof process !== 'undefined' && process.env
  ? Number.parseInt(process.env.MCP_REQUEST_TIMEOUT_MSEC ?? '', 10)
  : NaN;

5. Evaluated once at module load

The IIFE runs at import time. Setting the env var after importing the module has no effect. This should be documented, or the env var should be read lazily (at request time).

6. No upper bound

MCP_TOOL_CALL_MCP_REQUEST_TIMEOUT_MSEC=999999999 (31+ years) would be accepted. A reasonable ceiling (e.g., 3600000 / 1 hour) would prevent misconfiguration.

7. Changeset says minor

This adds no new API surface (no new function, class, or type). It changes behavior of an existing constant based on environment. This is a patch, not a minor.

I'd suggest: rename the env var, drop the try/catch, add runtime detection for non-Node environments, add tests, and change the changeset to patch.