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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds only 'by location', which duplicates the required location parameter already documented in the schema; it says nothing about pagination, result caps, or how browse differs from search.

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 tight phrase with the resource and scoping front-loaded; nothing is padded. It is efficient, though arguably terse enough that it leaves the search-vs-browse duality unstated.

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 100% schema coverage, an output schema, and read-only/open-world annotations, most of the load is carried by structured fields, so the description is minimally adequate. It is still thin for an 8-parameter tool because it never explains the search-vs-browse distinction or the effect of location scoping.

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% and every parameter, including the query/category interaction, is documented in the schema itself. The description adds no syntax, format, or constraint detail beyond what the schema provides, so 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?

The phrase 'Facebook Marketplace search/browse results by location' names a concrete verb (search/browse) and resource (Marketplace listings), and adds the location scoping. There is no marketplace sibling to disambiguate against, so this is clear, but it stops short of a 5 because it doesn't distinguish search from browse mode (that only appears in the 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?

The description gives no when-to-use guidance, no prerequisites, and no alternatives. The useful routing hint ('omit query with category for the browse feed') lives only in the query parameter schema, not the description, so the description itself carries none of this.

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