{"version":"2.1.238","anchor":"calling-a-tool-on-a-disabled-mcp-server-errors-instead-of-qu","canonical_anchor":"calling-a-tool-on-a-disabled-mcp-server-errors-instead-of-qu","heading":"Calling a tool on a disabled MCP server errors instead of quietly reconnecting","tier":"soon","area":"MCP","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.238\/e\/calling-a-tool-on-a-disabled-mcp-server-errors-instead-of-qu","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.238","markdown":"### Calling a tool on a disabled MCP server errors instead of quietly reconnecting\n\nCalling a tool on a disabled MCP server would tell you to re-enable it, but that path is off.\n\n**What**\n\nBefore 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.\n\n**Details**\n\n- The underlying error is \"MCP server disabled\".\n- Cached connections are evicted with a recorded reason: \"disabled\" for user-disabled servers, \"policy\" for servers blocked by policy.\n\n**Evidence**\n\n`re-enable it via \/mcp to use its tools`\n\n- Flag `tengu_mcp_discovery_cache_enable`: Not enough to say (read for one account on one subscription tier against v2.1.238; this account: no value returned, anonymous baseline: no value returned, compiled default: not a boolean we can read)\n- Area: MCP\n- Names: `\/mcp`\n- Tier: Nothing to try yet\n- Useful: 2\/5\n- Signal: 3\/5\n- Present in the build but not switched on"}