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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety and locality are covered. The description usefully adds that the category set is bounded to the French market, but says nothing about the shape of the returned list (names, IDs, count) or ordering.

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 short sentences, zero filler. The what-it-lists statement comes first and the caller instruction is front-loaded in second position, which is the right priority for a prerequisite tool.

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 parameterless enumeration tool with no output schema, the description supplies the domain (French market), the prerequisite role, and the constraint that advice needs a named category. Only the return-value format is unspecified, a minor gap for this simple listing endpoint.

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?

The tool takes zero parameters, so the baseline is 4; there is no parameter semantics to add. The description correctly implies a no-argument, enumerate-everything call, consistent with the empty input schema.

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 (Lists) and resource (product categories) plus the scope constraint (Pryx buying advice, French market). An agent can distinguish this enumeration endpoint from the sibling pryx_advice tool without opening either schema.

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?

"Call this FIRST" gives an explicit ordering rule, and the second clause explains why (advice requires a named category, never free text), which effectively routes the agent away from passing raw queries. It stops short of naming pryx_advice as the follow-up call, so it is clear but not fully explicit about the alternative.

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