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Sweep 28 Aug 2026 · 00:00Z Build v2.1.250 478 read Stable v2.1.236 Latest v2.1.250 Next v2.1.251 Feeds RSS JSON llms.txt
Reading a new release v2.1.251 Analysing changes · 2/5 Sorting the findings · 1/4 steps 470 findings $18.91 so far

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

Reference / Environment variables

MCP_TRUNCATION_PROMPT_OVERRIDE

A Claude Code environment variable, read out of the shipped bundle. It has been in the build since v2.1.138, including the newest one read.

What it is

Nobody has written a line about this one. It is not in any of Anthropic's reference tables and no changelog entry here carries a description of it. It is in the build, which is the whole of what this page can claim.

Presence across releases

ReleasesReadingDeclared typeDefault
2.1.245 – 2.1.250 5 releases never mined — —
2.1.160 – 2.1.243 75 releases in the build str —
2.1.138 – 2.1.159 20 releases in the build — —

A row reading never mined is a release with no archived bundle behind it. Nothing was read out of it, so nothing here says whether the name was in it. A declared type or a default is only ever what that release's own bundle stated.

Changelog entries naming it

No changelog entry here has ever named it. That is a statement about what has been written, not about the name: it has been in the build since v2.1.138 without anybody writing a line about it.

Documentation pages

None of Anthropic's documentation pages this site has a copy of carries this name.

Names beside it

Every environment variable in the inventory starting mcp, up to twelve of them.

MCP_CLIENT_SECRETNo description from anybody. 2.1.138 MCP_CONNECT_TIMEOUT_MSVery large MCP_TIMEOUT values are capped instead of overflowing and timing out instantly. 2.1.138 MCP_CONNECTION_NONBLOCKINGFive more environment variables, including stream and byte watchdogs, can be set in settings.json. 2.1.138 MCP_DISCOVERY_CACHEStartup no longer dials cached HTTP or SSE MCP servers; they restore from cache and connect on first use. 2.1.217 MCP_DISCOVERY_CACHE_MAX_STALE_SNo description from anybody. 2.1.217 MCP_DISCOVERY_CACHE_STRIKESNo description from anybody. 2.1.238 MCP_DISCOVERY_CACHE_TTL_SNo description from anybody. 2.1.217 MCP_OAUTH_CALLBACK_PORTAbout 220 environment variables now parse and validate in one place, including bounds checks. 2.1.138 MCP_OAUTH_CLIENT_METADATA_URLNo description from anybody. 2.1.138 MCP_PROTOCOL_NEGOTIATIONIn auto mode MCP connections would probe for a modern protocol and fall back to legacy, but nothing enables it. 2.1.221 MCP_REMOTE_SERVER_CONNECTION_BATCH_SIZETwo new env vars set how many MCP servers connect at once, local and remote. 2.1.138 MCP_SDK_GENERATIONNo description from anybody. 2.1.218

Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the environment variable does. All environment variables.