{"version":"2.1.321","anchor":"mcp-tool-schema-repair-now-also-handles-schemas-refused-insi","canonical_anchor":"mcp-tool-schema-repair-now-also-handles-schemas-refused-insi","heading":"Broken MCP tool input descriptions are now repaired when they arrive mid-conversation","tier":"notice","area":"MCP","scope":"individual","heads_up":false,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.321\/e\/mcp-tool-schema-repair-now-also-handles-schemas-refused-insi","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.321","markdown":"### Broken MCP tool input descriptions are now repaired when they arrive mid-conversation\n\nWhen the API refuses an MCP tool's input description sent inside a message, Claude Code can now replace it and retry instead of only fixing the tools list\n\n**Unclear.** This repair sits behind a server-controlled setting, and nothing shows whether it is switched on.\n\n**What**\n\nAn MCP server is an outside program that gives Claude Code extra tools. Each tool comes with a schema, a description of the inputs it accepts. When the API rejects a request because one of these schemas is invalid, Claude Code replaces the refused schema and tries again.\n\nThat repair used to look only in the main list of tools sent with a request. It now also finds refused schemas in tools that were added partway through a conversation, inside the messages themselves. When it repairs one of these, it replaces the schema and drops a streaming option attached to that tool. It can also now keep track of more than one refused schema for the same tool.\n\n**Why**\n\nA single faulty tool schema from an MCP server no longer breaks a conversation when that tool was added during the conversation rather than at the start.\n\n- Flag `tengu_calm_crescent`: Not enough to say (read for one account on one subscription tier against v2.1.321; this account: no value returned, anonymous baseline: no value returned, compiled default: on) These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.\n- Area: MCP\n- Tier: You'll notice\n- Useful: 2\/5\n- Signal: 2\/5\n- Scope: individual\n- Heads-up: no"}