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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so the safety profile is clear. The description adds useful behavioral context by defining what output is returned (keyword rankings, position/popularity) and noting the ASO plan requirement for the API token. This goes beyond the structured annotations.

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 concise, front-loaded with the core purpose, and each sentence serves a function: explaining output, showing usage, and noting prerequisites. It is slightly redundant with schema descriptions for app_id and _apiKey, but remains well-organized and scannable.

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, idempotent lookup with fully documented parameters and no output schema, the description covers the essential invocation details: what it returns, example usage, and authentication requirements. It could be more complete by describing result shape or pagination, but this is not critical for calling the tool 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 coverage is 100%, so the schema fully documents app_id, device, _apiKey, and country. The description restates app_id's accepted formats and gives an example, but adds little meaning beyond the schema. Baseline 3 is appropriate because the schema carries the parameter documentation burden.

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 clearly states the tool's purpose: ASO keyword rankings for an app, including the keywords it ranks for and store position/popularity. It distinguishes itself from sibling tools like appfollow_ratings and appfollow_reviews by focusing on keyword rankings rather than ratings or reviews. The example call reinforces the exact behavior.

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 provides a concrete example and explains the prerequisite that ASO must be enabled on the token. However, it does not explicitly state when to prefer this tool over alternatives or when not to use it. The usage context is implied rather than contrasted with sibling tools.

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