{"rules_version":"2026-10-18.1","samples":[{"label":"endpoint-shaped","request":{"name":"getUser","description":"Get a user","inputSchema":{"type":"object","properties":{"id":{"type":"string"}},"required":["id"]}},"response":{"rules_version":"2026-10-18.1","name":"getUser","shape":"endpoint-shaped","findings":[{"id":"endpoint-shaped-name","kind":"heuristic","message":"The name starts with get, list, create, update, delete, or set, followed by another word. Those six verbs are the ones in the cited examples. A 2026-08-27 practitioner note says that one MCP tool per REST endpoint loads every endpoint into the context window, and that a tool should be a capability instead. This is not a requirement of the MCP specification.","source":{"url":"https://x.com/arpit_bhayani/status/2092973180306833697","author":"@arpit_bhayani","date":"2026-08-27","note":"Map an MCP tool to a capability, not to one REST endpoint"},"resource":"toolcard://answers/mcp-tools-mapped-1-to-1-onto-a-rest-api"},{"id":"thin-description","kind":"heuristic","message":"The description is missing or shorter than 40 characters. 40 is Toolcard's cutoff, not a number from the source. A 2026-10-13 practitioner note says to write the name and description in the words developers use, because a vocabulary mismatch is one reason an agent never calls the tool.","source":{"url":"https://x.com/waldekm/status/2109907029963780339","author":"@waldekm","date":"2026-10-13","note":"Write the tool name and description in the words developers use"},"resource":"toolcard://answers/mcp-server-loads-but-the-agent-never-calls-it"},{"id":"description-echoes-name","kind":"heuristic","message":"The description only repeats words already in the name. The same 2026-10-13 note says the description has to use the words a developer would actually type.","source":{"url":"https://x.com/waldekm/status/2109907029963780339","author":"@waldekm","date":"2026-10-13","note":"Write the tool name and description in the words developers use"},"resource":"toolcard://answers/mcp-server-loads-but-the-agent-never-calls-it"}],"stored":false}},{"label":"not-endpoint-shaped","request":{"name":"manage_user","description":"Create or update a user account and its permissions, then return a short summary of what changed.","inputSchema":{"type":"object","properties":{"action":{"type":"string","description":"create, update, or set_permissions"},"email":{"type":"string"}},"required":["action"]}},"response":{"rules_version":"2026-10-18.1","name":"manage_user","shape":"not-endpoint-shaped","findings":[],"stored":false}}]}