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

No annotations are supplied, so the description carries the full burden, and it does meaningful work by explaining the semantics of the three returned numbers (median, 25th-percentile 'good price', 75th 'overpaying' threshold), which no output schema covers. It is silent on error behavior for an unknown slug and on rate limits or auth, which keeps it out of the top band.

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, front-loaded with the core behavior and free of filler. The second sentence is compact but arguably does not earn its place given that it conflicts with the required parameter.

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 one-parameter read tool with no annotations and no output schema, the description adequately covers what is returned and how to read it. The unresolved tension between the 'no slug' discovery instruction and the required parameter is the main completeness gap an agent would trip over.

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 the schema already gives example slugs, so the baseline would be 3. The description's only extra parameter claim, that omitting the slug returns a category list, contradicts the schema's required: ["category"], making the added meaning actively misleading rather than additive.

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 title and description state a specific verb/resource: median cost per unit for one tracked category, and they even define what the returned percentile figures mean. It never names the siblings unit_price or bigger_pack, so an agent must infer how this differs from a generic unit-price tool.

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?

There is one concrete usage hint, 'Call with no known slug to get the list of categories', but no guidance on when to prefer this over unit_price or bigger_pack. That single hint also conflicts with the schema, where category is a required parameter, so the agent is left unsure whether an omitted-slug discovery call is legal.

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