trw_heartbeat

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries the full burden. It fully discloses the rate-limiting behavior, the short-circuit condition based on a 60-second window, the state persistence in pins.json, the output structure on success, and the error case for missing pin. This is a comprehensive behavioral disclosure.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is appropriately sized and front-loaded with a one-line summary. It uses clear section headers (Use when, Rate-limit, Input, Output) and bullet points for readability. Every sentence adds value without waste.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Despite no output schema, the description lists the result fields (run_id, last_heartbeat_ts, etc.) and error case. Given the tool's simplicity (one optional parameter), the description is complete and provides sufficient context for an AI agent to use it correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

With schema description coverage at 0%, the description must compensate. It does so by explaining the only parameter 'message' as 'optional context string logged alongside the heartbeat event.' This adds meaning beyond the schema's default and type.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose: 'Refresh the caller's pin heartbeat and append a heartbeat event.' It uses specific verbs and resources, and given the sibling tools like trw_init, trw_checkpoint, and trw_probe, the description provides context that distinguishes it as a keep-alive mechanism for long-running campaigns.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description explicitly provides usage scenarios: 'Use when: - A long-running campaign needs to keep its pin alive between work units. - You want to probe whether the current run is stale enough to checkpoint.' This gives clear guidance on when to use this tool versus alternatives.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.