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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It discloses a key behavioral trait: it returns summary statistics rather than detailed domain results, and that it is faster. However, it does not explicitly state whether the operation is read-only or describe any side effects, though the verb 'Check' strongly implies a safe query. The disclosure is adequate but not rich.

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 only two sentences, with the purpose and primary differentiator front-loaded in the first sentence and parameter guidance in the second. Every word contributes value, and there is no repetition of schema 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?

For a relatively simple read-only summary tool with no output schema, the description covers purpose, scope, speed trade-off, and all parameters with format examples. It does not describe the response format, but 'summary statistics' gives a reasonable expectation. Overall, the essential information an agent needs to invoke it correctly is present.

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 0%, so the description must compensate for the bare input schema. It does: it marks keyword as required with an example ('example'), and identifies registries and tlds as optional with comma-separated format examples ('verisign,pir' and 'com,net'). This adds meaningful semantic guidance for all three parameters beyond their data types.

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 the action: 'Check keyword availability summary statistics' and explicitly contrasts with 'without detailed domain results (faster)', which distinguishes it from the sibling tool checkKeywordAvailability. This gives an agent a precise understanding of what the tool does and how it differs from related 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 phrase 'without detailed domain results (faster)' implicitly tells the agent when to use this tool: when summary statistics are sufficient and speed is preferred over detailed results. It does not explicitly name the alternative tool, but the sibling list includes checkKeywordAvailability, making the contrast clear. No exclusions or when-not-to-use guidance is provided.

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