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

Annotations already cover read-only, idempotent, non-destructive behavior. The description adds meaningful behavioral context beyond annotations: it returns only summary statistics, never per-domain results, and is faster than the full checkKeywordAvailability tool. This is valuable but does not detail what the summary statistics contain or any response format.

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 one tight sentence that front-loads the core purpose and immediately states key behavioral distinctions. The repeated tool name prefix is slightly redundant, but the rest is compact and every clause adds meaningful information.

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?

Parameters are fully documented in the schema and safety behavior is covered by annotations, so the description does not need to repeat those. However, there is no output schema, and the description only vaguely says 'summary statistics' without explaining what statistics are returned. An agent might still be uncertain whether the output satisfies a user's request.

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%, with clear explanations for tlds, keyword, and registries. The description does not add any parameter-level guidance, which is acceptable since the schema already documents each parameter fully. No extra semantic value is needed beyond what the schema provides.

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 defines the tool as checking keyword availability across TLDs and registries, and explicitly distinguishes it from the sibling checkKeywordAvailability by emphasizing summary-only results and faster execution. This gives an agent a precise idea of what the tool does and how it differs from similar 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?

The description gives clear selection context: use this tool when only summary statistics are needed and when faster results matter, while explicitly noting that per-domain results are not included. It names the alternative tool but does not fully state 'use checkKeywordAvailability when per-domain results are required,' leaving a small gap in explicit when-not-to-use guidance.

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