Source Intelligence

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.

All of v2.1.238 Home All releases olderv2.1.237 v2.1.239newer
Claude Code v2.1.238

Calling a tool on a disabled MCP server errors instead of quietly reconnecting

Not switched on
Useful2 Signal3
MCP

Calling a tool on a disabled MCP server would tell you to re-enable it, but that path is off.

The disabled-server error only runs when the MCP discovery cache flag is on; otherwise the old quiet reconnect applies.

Feature flag
tengu_mcp_discovery_cache_enable 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 v2.1.238: not a boolean we can read

Read once, for one account on one subscription tier, against v2.1.238. It isn't a statement about your account. What a flag value here can and cannot tell you

/mcp
What

Before reusing a cached or in-flight connection, Claude Code now checks whether the MCP server has been disabled and, if so, fails with text telling you to re-enable it via /mcp to use its tools. This only runs when the MCP discovery cache flag tengu_mcp_discovery_cache_enable is on; otherwise the old behaviour applies.

Details
  • The underlying error is "MCP server disabled".
  • Cached connections are evicted with a recorded reason: "disabled" for user-disabled servers, "policy" for servers blocked by policy.
Evidence

re-enable it via /mcp to use its tools

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

See this entry in the whole of v2.1.238 →