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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is covered. The description adds no behavioral context of its own: it does not mention that end_cursor drives pagination, that radius filtering likely requires coordinates, or how results are ordered by default. Beyond restating the filters, it contributes nothing the structured fields don't already carry.

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 zero filler; the core verb and resource lead and the qualifiers follow. Nothing is padded or repeated from the title.

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?

Since an output schema exists, return values need no explanation. However, for an 11-parameter search tool with no required fields, the description omits meaningful operational detail: how pagination works, that latitude/longitude pair with filter_radius_km, and which defaults apply. Adequate but with clear gaps.

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%, so all 11 parameters are already documented in the schema, which sets the baseline at 3. The description names four filter categories that map onto existing parameters but adds no new semantics such as coordinate/radius pairing rules or sort behavior.

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 ('Search') and resource ('Marketplace rental property listings') and enumerates the filter axes (bedrooms, bathrooms, location, price). This separates it from generic siblings like facebook_marketplace_search or facebook_marketplace_vehicles, though the distinction is implied by the word 'rentals' rather than stated explicitly.

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 and no routing to alternatives such as facebook_marketplace_search (general listings) or facebook_marketplace_vehicles. The agent must infer selection purely from the token 'rentals' in the name, with no stated prerequisites or exclusions.

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