{"rule_id":"AB-164","category":"machine_readable","icon":"❗","title":"Error catalog endpoint","short_description":"Your site serves a JSON error catalog at /api/meta/errors or /errors.json with error codes and descriptions.","user_value":"AI agents can programmatically look up error codes and meanings, enabling intelligent retry and error-handling decisions.","wrong_example":"GET /api/meta/errors → 404","right_example":"[{\"code\":\"RATE_LIMITED\",\"description\":\"Too many requests\"},{\"code\":\"INVALID_INPUT\",\"description\":\"Validation failed\"}]","effort_hint":"moderate","estimated_cost":"$0","severity":"low","pillar":"discovery","version":"1.0.0","counted_in_score":true,"check":{"type":"semantic_validation","sources":["error_catalog"]},"fix":{"eligible":true,"type":"deterministic","note":"Serve a JSON error catalog at /api/meta/errors (or /errors.json, /api/errors) with an array of error codes and descriptions"},"checklist_anchor":"#AB-164","checklist_url":"/agent-readiness-checklist#AB-164","html_url":"/rules/AB-164","json_url":"/rules/AB-164.json","related_rules":[{"rule_id":"AB-010","title":"Machine-Readable Pricing","category":"machine_readable"},{"rule_id":"AB-011","title":"Rate Limits Declared","category":"machine_readable"},{"rule_id":"AB-012","title":"Structured Error Responses","category":"machine_readable"},{"rule_id":"AB-020","title":"MCP Tools List","category":"machine_readable"},{"rule_id":"AB-021","title":"MCP Tool Calls","category":"machine_readable"},{"rule_id":"AB-022","title":"MCP Streaming Support","category":"machine_readable"},{"rule_id":"AB-109","title":"Agent Card version 1.0.0+","category":"machine_readable"},{"rule_id":"AB-163","title":"Skill.json (JSON-LD) availability","category":"machine_readable"}]}