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

Annotations already mark idempotentHint true, openWorldHint true, and readOnlyHint false. The description adds meaningful behavior beyond annotations: it is free, only re-checks names still marked 'not checked,' and returns a run unchanged if all names are resolved. This aligns with and enriches the idempotency annotation without contradiction.

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 two sentences with no filler. The main action is front-loaded, followed by cost and idempotency conditions. Every clause adds useful information, making it both concise and complete for the tool.

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 single-parameter tool with no output schema, the description covers purpose, cost, and behavioral edge cases. It could mention the return type or possible external side effects (e.g., live registrar queries), but the idempotency hint and openWorldHint supplement enough context for correct invocation.

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 schema covers the single 'id' parameter fully with 'The brand-name run ID to backfill availability for.' The description reinforces the run context but adds no new parameter-level details such as format or examples. With 100% schema coverage, the baseline of 3 is appropriate.

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 a specific verb and resource: 'Fill in domain availability and prices for names in a run that were saved without them.' It explains the context (registrar throttled at generation time), which makes the tool's purpose concrete and distinct from siblings like get_brand_names or check_credits.

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 to use the tool: after a run has names without availability due to throttling. It also clarifies that only unresolved names are re-checked, so an agent can decide whether calling it will have effect. It does not explicitly name alternatives, but no sibling does the same thing, so the context is sufficient.

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