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

Annotations already cover readOnly/idempotent/non-destructive, yet the description still adds real value: 'spends nothing' discloses the credit/cost profile, and the note that popularity, difficulty, relevance and opportunity are modeled 0-100 indexes rather than store-reported search volume prevents serious misinterpretation of the returned numbers. It does not disclose behavior when run_id refers to an unfinished or unknown run.

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?

One dense but well-ordered paragraph: what is returned first, the metric-meaning caveat second, the safety/cost note last. Every clause carries information; no filler.

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?

There is no output schema, so the description must sketch the return shape, and it does so concretely (per-country candidates, score breakdowns, top apps, listing variants with counters/checks/coverage). Only the lifecycle gap — how to get a valid run_id and what happens for an incomplete run — is missing.

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?

With a single parameter at 100% schema coverage, the schema already explains run_id. The description only adds the constraint that the run must be finished, which is a modest semantic contribution beyond the schema's 'Run id.'

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?

States a specific resource and scope: the full result of a *finished* Wow Keywords run, broken down by country into scored candidates and listing variants. The word 'finished' implicitly separates it from wow_keywords_status, but no sibling is named explicitly, so the agent must infer the routing itself.

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?

'Finished run' implies the precondition, and 'Read-only; spends nothing' signals it is safe to poll, but the description never says to check wow_keywords_status first or what to do if the run is still in progress. Usage is implied rather than stated.

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