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Sweep 22 Oct 2026 · 04:32Z Build v2.1.308 527 read Stable v2.1.308 Latest v2.1.308 Next v2.1.308 Feeds RSS JSON llms.txt llms-full.txt Unofficial

Claude Code v2.1.248 ·

MCP output token cap resolution

MAX_MCP_OUTPUT_TOKENS is still honoured first, but it's no longer sanity-checked as a number.

Use it now No documentation found Improvements
JSON All of v2.1.248
Use it nowTier: how much it should matter to you
2Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
MCPArea: what it touches
ImprovementsKind: in v2.1.248,
What probably matters to youSection of the release
What

The limit on how much output an MCP tool may return still reads the MAX_MCP_OUTPUT_TOKENS environment variable first, then a server-side config value, then a built-in default. The environment value is no longer checked for being a finite number before use.

Details
  • Server config comes from tengu_velvet_ibis, whose fallback is an empty object, so with no server value the built-in default applies.
Evidence

tengu_velvet_ibis

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Read from
Names in the bundleMAX_MCP_OUTPUT_TOKENS
Feature flag
tengu_velvet_ibis Not enough to say

Nothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.

This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.248: not a boolean we can read

Read once, for one account on one subscription tier, against v2.1.248. It isn't a statement about your account. What a flag value here can and cannot tell you

Since it was published

The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.

Confirmed since Anthropic's documentation has since written up MAX_MCP_OUTPUT_TOKENS, on Build an MCP server for Claude. | Maximum tool result size | \~150,000 characters | 25,000 tokens, configurable with `MAX_MCP_OUTPUT_TOKENS` | connectors/building/index see the edit
What has happened since
Flag reading moved The flag server now returns [] for tengu_velvet_ibis, read as this account. A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.
Flag reading moved The flag server now returns nothing at all, having stopped carrying it for tengu_velvet_ibis, read as this account. A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.

See this across every release →

How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agreesAnthropic's documentation has since written up MAX_MCP_OUTPUT_TOKENS, on Build an MCP server for Claude.

See this entry in the whole of v2.1.248 →

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