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

Annotations only declare readOnlyHint=false and destructiveHint=false; the description goes further by disclosing the credit cost and a caching rule ('the same keyword+market re-queried within a week is free'), which materially affects invocation strategy. It does not cover auth requirements or result limits, but no annotation is contradicted.

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?

Front-loads the output shape, then usage, pairing, and cost in separate sentences, each earning its place. The opening sentence is dense but still readable, and no sentence is 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?

With no output schema, the description carries the return-value burden and does so by enumerating the per-position fields. Combined with triggers, the sibling pairing, and the credit/caching behavior for a 2-param tool, nothing essential 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?

Schema description coverage is 100% and both parameters already carry descriptions, including the list of market codes for location_code, so the baseline is 3. The description reinforces the shape ('one keyword in one market') but adds no syntax or default detail beyond what the schema states.

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 precise verb and resource ('Who holds the Google top 10 for one keyword in one market') and enumerates the exact fields returned per position: domain, URL, homepage vs inner page, domain rating, estimated monthly organic traffic. It is unmistakably distinct from research_keyword_volume, which it explicitly names as a complement.

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?

Gives three concrete trigger scenarios ('who ranks for a keyword', 'whether a keyword is winnable', 'which slot is the weakest') and routes the agent to research_keyword_volume for volume and difficulty. The alternative is named with the condition that selects it, leaving little to inference.

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