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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so safety is covered. The description adds genuinely new operational context not present in structured fields: no API key required and a per-IP daily free-tier rate limit, which matters for call planning.

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?

Three short sentences, front-loaded with what is extracted and how it is ranked, then use case, then the constraint. Nothing is redundant with the name or schema.

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 read-only extraction tool with full schema coverage, annotations covering safety, and no output schema, the description supplies what is missing (ranking, competitor relevance, free-tier limits). It could be tighter on return shape (e.g., how many keywords come back by default), but that is largely covered by the 'max' parameter.

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% and all four parameters (store, store_id, country, max) are fully documented in the schema, including the store_id cross-reference to sonar_app_search. The description adds no parameter-level detail beyond that, so the baseline 3 applies.

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 ('Extract the most likely target keywords from an app's title and description') and adds ranking behavior. It is clear what the tool produces, though it never names or contrasts the closely related siblings (sonar_app_keywords, sonar_competitor_keywords, sonar_keyword_suggestions), so an agent must infer the distinction from the inputs alone.

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?

'Useful for understanding what an app (yours or a competitor) is optimizing for' implies the use case and adds the free-tier constraint, but there is no explicit when-to-use vs. when-not, and no alternative tool is named despite several keyword-oriented siblings existing.

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