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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safe, live-read nature is covered. The description adds that the output is aggregated counts organized by a three-level taxonomy (department/category/subcategory), which is useful behavioral context. It stops short of describing shapes, counts semantics, or coverage, so a 3 is appropriate.

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?

A single front-loaded sentence with no filler; the resource and its facet hierarchy are stated up front. Every word earns its place.

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?

With an output schema present, the description need not explain return values, and annotations cover the safety profile. Given a one-param facet tool this is nearly complete; the only gap is the lack of explicit relationship to depop_search for routing.

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?

Only one parameter ('query', free-text keyword search) with 100% schema description coverage, so the schema already fully documents it. The description adds nothing about query syntax or accepted values beyond the schema. Baseline 3 is correct when the schema does the heavy lifting.

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?

Clear verb+resource: returns result-count breakdowns (facets) per department/category/subcategory for a Depop search query. This distinguishes it from the plain listing siblings like depop_search. It does not explicitly name depop_search as the alternative, but the facet framing is unambiguous.

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?

Usage is only implied via the noun 'facets' and 'result-count breakdowns'. There is no explicit when-to-use statement, no indication that this should be called before or alongside depop_search to narrow a query, and no exclusions. An agent can infer the purpose but gets no routing guidance.

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