{"rule_id":"AB-162","category":"actionability","icon":"💓","title":"Heartbeat.md availability","short_description":"Your site serves /heartbeat.md with YAML frontmatter, providing a periodic check-in routine for AI agents.","user_value":"AI agents can periodically check your service health and status via a machine-readable heartbeat endpoint, enabling self-healing workflows.","wrong_example":"GET /heartbeat.md → 404","right_example":"---\nstatus: operational\nlast_check: 2026-09-07\n---\n# Heartbeat\nService is operational.","effort_hint":"quick","estimated_cost":"$0","severity":"low","pillar":"understandability","version":"1.0.0","counted_in_score":true,"check":{"type":"semantic_validation","sources":["heartbeat"]},"fix":{"eligible":true,"type":"deterministic","note":"Serve /heartbeat.md with Markdown content and YAML frontmatter (---) to provide a periodic check-in routine for AI agents"},"checklist_anchor":"#AB-162","checklist_url":"/agent-readiness-checklist#AB-162","html_url":"/rules/AB-162","json_url":"/rules/AB-162.json","related_rules":[{"rule_id":"AB-007","title":"Guide and API Consistency","category":"actionability"},{"rule_id":"AB-008","title":"Authentication Declared","category":"actionability"},{"rule_id":"AB-009","title":"Capability Coverage","category":"actionability"},{"rule_id":"AB-074","title":"A2A Agent Card Published","category":"actionability"},{"rule_id":"AB-075","title":"A2A Agent Card Verified","category":"actionability"},{"rule_id":"AB-085","title":"MCP Server Name Present","category":"actionability"},{"rule_id":"AB-086","title":"MCP Auth Discovery Resolves","category":"actionability"},{"rule_id":"AB-146","title":"Operation descriptions","category":"actionability"},{"rule_id":"AB-159","title":"Business constraints documented","category":"actionability"},{"rule_id":"AB-166","title":"next_call pattern in API responses","category":"actionability"}]}