domains_check_availability

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

Annotations already declare readOnlyHint=true, so the read-only nature is covered structurally. The description adds valuable behavioral context with the heavy rate limit (1 request/10 seconds) and positions the tool as a final confirmation step, without contradicting 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?

Four short, purposeful sentences: a one-line purpose, a warning, an alternative tool reference, and a usage constraint. No redundancy, with the most critical operational caveat (rate limit) front-and-center.

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-parameter read-only tool with an output schema, the description covers purpose, rate limiting, when-to-use, and alternatives. It doesn't need to explain return values because the output schema exists, making the description contextually complete.

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?

Input schema provides complete documentation of the single 'domain' parameter with an example format, so schema coverage is 100%. The description does not add parameter-level meaning beyond 'domain name to check'; however, baseline is 3 because the schema carries the full burden.

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 opens with a specific verb+resource ('Check domain availability and pricing') and clearly distinguishes itself from sibling pricing_get by directing price comparisons to that tool. It also narrows its scope to confirming specific domain availability, which sets it apart from list/read tools.

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?

Explicitly states when to use: only when needing to confirm a specific domain is available. It names the alternative (pricing_get) for price comparisons and highlights the rate-limit constraint, giving agents clear decision rules.

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