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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. Beyond that the description adds nothing behavioral: no pagination behavior for end_cursor, no note that results are public/open-world listings, no rate-limit or auth context. With annotations doing the heavy lifting, the description contributes almost no extra behavioral value.

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 that names the operation before the filter list, with no filler or redundancy. It is appropriately sized for its content, though the content itself is thin.

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?

An output schema exists, so return values need not be explained. However, for an 8-parameter paginated search tool with all-optional inputs, the description says nothing about defaults, how end_cursor pagination is expected to be used, or how this differs from the general marketplace search sibling — leaving real gaps for correct invocation.

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% across all 8 parameters, so the baseline is 3. The description's filter list (location, price, mileage, year) roughly mirrors schema fields, though "year" corresponds to no actual parameter and "mileage" only exists indirectly via sort_by=VEHICLE_MILEAGE_ASCEND, so the description neither compensates nor misleads meaningfully.

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 clear verb and resource ("Search Marketplace vehicle listings") plus the filter dimensions, which is enough for an agent to know it retrieves vehicle ads. It does not, however, distinguish itself from the closely related siblings facebook_marketplace_search, facebook_marketplace_listing, and facebook_marketplace_rentals, so it falls short of a 5.

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 no when-to-use guidance, no mention of when to prefer the generic facebook_marketplace_search or facebook_marketplace_rentals instead, and no prerequisites. The only routing signal is the word "vehicle" in the resource name, which is implied rather than stated.

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