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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so safety is covered. The description adds genuinely new behavior: it discloses the authentication model (no API key needed) and a rate limit ('limited daily use per IP'), which the agent cannot learn from the schema or 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?

Three sentences, each load-bearing: what it does, what it returns, and the auth/rate-limit constraint. The core purpose is front-loaded with zero padding.

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 naming the returned fields (name, developer, category, rating, reviews, installs, price) usefully compensates, and auth plus rate limits are covered. The remaining gap is routing among near-identical siblings, which is unaddressed.

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% — store, country, and store_id each carry their own format documentation, including iOS numeric track ID vs Android package name. 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?

States a specific verb and resource ('look up a single app by its store ID') and enumerates the returned metadata, so the agent knows exactly what it gets. However, it never distinguishes itself from close siblings like sonar_get_app or sonar_app_overview, leaving the agent to guess which lookup tool to pick.

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 notes it works without an API key on a free tier with limited daily use per IP, which is useful operational context. But it gives no guidance on when to use this versus sonar_get_app, sonar_app_overview, or sonar_app_search, and no prerequisite or exclusion conditions.

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