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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower, yet the description still adds real behavioral context: HTTP 200 whenever the server is up, `ready` is false during post-restart ingestion, and paid endpoints return 503 without charging until then. That is useful operational detail beyond the annotations.

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 with the cost signal ('Free.') front-loaded. The telegraphic fragments ('Liveness and store readiness.') are efficient rather than wasteful, though slightly clipped.

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?

With an output schema present and annotations covering the safety profile, the description needs only to add operational context — which it does by explaining the 200/503 behavior and the `ready` flag. Nothing critical for invoking a zero-parameter health check is missing.

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?

The tool takes zero parameters, so the baseline is 4. The description correctly introduces no parameter discussion and instead explains the meaning of the `ready` field the agent will see.

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 function clearly: liveness and store readiness check on the service. It is easy to tell apart from data-listing siblings like spot_latest or capacity_board, though it does not distinguish itself from the sibling `status`, which plausibly overlaps in intent.

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 implies when this is useful (checking whether the server and store are up) and explains the practical consequence of `ready` being false for paid endpoints. However, it never explicitly says when to call this versus the sibling `status`, nor does it state any preconditions or exclusions.

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