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

The description discloses non-obvious behavior beyond annotations: credit is charged upfront and refunded only on provider failure, zero qualifying ideas still consume the credit, near-duplicates/navigational/other-city keywords are dropped, and a keyword without a cluster becomes the pillar of a new one. This is far richer than the annotations alone and does not contradict them.

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 dense but every sentence carries necessary operational detail: main behavior first, then credit mechanics, confirmation requirement, and website_id condition. There is no filler or repetition.

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 mutating tool with cost implications, the description covers prerequisites, confirmation behavior, refund policy, filtering logic, and parameter conditions. Combined with 100% schema coverage and the presence of an output schema, nothing essential is missing for an agent to invoke it correctly.

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%, so the baseline is 3. The description mostly restates what the schema already says about confirm, keyword_id, and website_id, though it does add the multi-website condition nuance. It does not materially exceed the schema's parameter documentation.

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 states a specific verb and resource: 'Grows the topic cluster of a keyword' and explains the concrete behavior (fetches related ideas, filters for semantic closeness, adds at most 30). This clearly differentiates it from sibling tools like research_keywords or add_keywords, which serve different purposes.

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?

It gives clear operational context: confirm=true is required to acknowledge the credit charge, without it only the cost and balance are returned, and website_id is needed for multi-website accounts. It does not explicitly mention when to prefer this tool over alternatives, so it stops short of a 5.

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