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

Annotations already declare readOnly, idempotent, non-destructive behavior, so the description does not need to repeat that. It adds meaningful behavioral context by clarifying that the result is limited to the scanned substring of top results and by defining the exact output phrasing, including the 'not in top N' case.

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 a single tightly written two-sentence passage. It front-loads the core purpose and then gives an exact output format example. There is no fluff or repetition of schema fields.

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?

The behavior is fully specified for an agent: the lookup scope is clear, the result interpretation is provided, and annotations cover safety. The existing input schema and output schema allow a new agent to call this tool without ambiguity. No extra edge cases seem material enough to require mention.

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 coverage is 100%, and each parameter has a description. The tool description adds value by explaining the output in terms of 'scanned results', but it does not add substantial parameter-level semantics beyond the schema; the baseline of 3 is appropriate.

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 ('Look up'), a precise resource (current keyword ranking of a specific app), and the exact scope (store and country). It also distinguishes itself from sibling tools like get_keyword_history or get_keyword_overview by calling out 'current' ranking and the output format, so the agent can select it appropriately.

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 description implies when to use the tool — checking a current ranking for a keyword — but it does not explicitly name alternatives or state when not to use it. The sibling list is not referenced in the description, leaving the agent to infer the distinction between current ranking and related get_keyword_overview/get_keyword_history tools.

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