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

With no annotations, the description carries the burden of explaining behavior, and it does by describing a non-mutating ranking/analysis operation and listing the evidence signals considered. It does not discuss return format, latency, or auth, but 'Rank... by evidence' and 'before building' make the read-only analytical nature clear.

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?

Two sentences, with the tool's action and evidence criteria front-loaded and the usage instruction right after. Every clause adds information; there is no 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?

The description gives purpose and timing but, with no output schema and no parameter explanations, it does not tell an agent what the ranked result looks like or how the optional inputs affect it. For a 3-parameter tool with zero schema descriptions, this is a meaningful completeness gap.

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 0% and the description never mentions limit, storefront, or min_rating_count, nor how they shape the ranking. The parameter names and defaults in the schema are the only source of meaning, so the description fails to compensate for the missing schema documentation.

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 opens with a specific verb-resource pair: 'Rank app categories by evidence that users already pay inside them.' It then enumerates concrete evidence signals (Top-Grossing chart presence, upfront charges, paywall language, review depth), making the tool's job distinct from siblings like find_unmet_demand or market_stats.

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?

It explicitly says when to call it: 'Call this before building to confirm a market monetises.' It does not name sibling tools or give when-not-to-use conditions, so it falls just short of a full 5.

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