{"version":"2.1.221","anchor":"mcp-client-constructed-with-a-json-schema-validator-and-expl","canonical_anchor":"mcp-client-constructed-with-a-json-schema-validator-and-expl","heading":"MCP client constructed with a JSON Schema validator and explicit listChanged settings","tier":"notice","area":"MCP","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.221\/e\/mcp-client-constructed-with-a-json-schema-validator-and-expl","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.221","markdown":"### MCP client constructed with a JSON Schema validator and explicit listChanged settings\n\nMCP servers announcing tool or prompt list changes will not cause Claude to refetch them.\n\n**What**\n\nClient construction and request-handler registration were reworked, and server list-changed notifications explicitly do not trigger refetching.\n\n**Details**\n\n- The Client is created with `jsonSchemaValidator`, the negotiation config, and a `listChanged` block setting `autoRefresh: !1, debounceMs: 0` with no-op `onChanged` for tools, prompts and resources.\n- Request handlers are registered by method-name strings (`\"roots\/list\"`, `\"elicitation\/create\"`) rather than schema objects.\n- A set of recognised JSON Schema draft URIs, draft-04 through 2019-09 plus the unversioned ones, is now kept in the module.\n\n**Evidence**\n\n`jsonSchemaValidator`\n\n- Area: MCP\n- Tier: You'll notice\n- Useful: 2\/5\n- Signal: 0\/5"}