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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 v2.1.250 Feeds RSS JSON llms.txt

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_DISCOVERY_CACHE

A Claude Code environment variable, read out of the shipped bundle. It has been in the build since v2.1.217, including the newest one read.

What it is

Startup no longer dials cached HTTP or SSE MCP servers; they restore from cache and connect on first use.

Not Anthropic's. This is the line from the earliest changelog entry here that named it, v2.1.221.

Presence across releases

ReleasesReadingDeclared typeDefault
2.1.245 – 2.1.250 5 releases never mined — —
2.1.217 – 2.1.243 26 releases in the build triBool —

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

  1. v2.1.238The MCP discovery cache is now off unless explicitly turned on

    The MCP discovery cache flipped from on-by-default to off unless the server or you enable it.

    named in this entry

  2. v2.1.238MCP servers can connect lazily from a cached entry

    Tool calls to a remembered MCP server could dial it on demand, but the cache behind it is off.

    named in this entry

  3. v2.1.221MCP servers can start from a discovery cache and connect lazily

    Startup no longer dials cached HTTP or SSE MCP servers; they restore from cache and connect on first use.

    named in this entry

  4. v2.1.221MCP servers can start in a new "cached" state instead of blocking on connect

    MCP servers with a saved cache now show tools instantly and only connect when you first use them.

    named in this entry

Documentation pages

A reference table page is one whose own table defines this name, and it is where the description above came from. A page that mentions it carries the name somewhere in its text and may say nothing about it at all. Every page carrying it.

Names beside it

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

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

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.