Report this agent as alive

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

Annotations declare readOnlyHint=false and idempotentHint=true, and the description adds a genuine behavioral fact not in the annotations: the call is refused unless an activity expectation is declared. It does not spell out what the heartbeat actually resets on Rein's side (presumably a liveness timer) or what the caller observes on refusal, which is the only remaining gap.

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?

Three short sentences, front-loaded with the purpose before the routing rule and the refusal condition. No filler and no repetition of the title or schema.

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?

For a one-optional-parameter, no-output-schema tool with annotations present, the description covers purpose, alternatives, and the refusal precondition. Only the observable consequence of a successful heartbeat is unstated, which is minor at this complexity.

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?

Schema description coverage is 100% and the single optional 'note' parameter is fully documented in the schema as operator-facing text. The description adds nothing about the parameter, so the baseline 3 applies.

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?

States a specific verb and target ('Tell Rein this agent is still working') plus the mechanism it feeds ('dead-man monitoring'). It also names a sibling, rein_fetch, and explains the relationship, so an agent can separate this from the other rein_* tools without reading their schemas.

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?

Gives an explicit when ('only needed when the agent is running but not buying anything'), an explicit when-not via the alternative ('every rein_fetch is already a sighting'), and a precondition ('refused when no activity expectation is declared'). All three routing questions are answered in the text.

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