Search Facebook Marketplace

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

With no annotations, the description fully explains the behavioral traits: it's disabled by default, violates Facebook's ToS, returns an error unless configured, and points to the stub's docstring for further details. This is exemplary transparency, going far beyond a simple 'searches Facebook Marketplace'.

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?

The description is concise, using three sentences to convey the core purpose, the disabled state, and the required setup. Every sentence adds value, and the warning is front-loaded. There is no redundant or filler content.

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?

The description thoroughly covers the tool's operational state and dependencies, which is useful for understanding its current limitations. However, it omits parameter semantics entirely, which is essential for correct invocation. Given that the output schema exists, return values are not a gap, but the parameter explanations are missing, making the description incomplete for actual use.

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 schema has 3 parameters (query, location, radius_km) with 0% schema description coverage. The description does not mention any of these parameters or their meanings, leaving the agent entirely to guess from parameter names. No compensation is provided for the missing schema descriptions.

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 description clearly states the tool's action as 'Search Facebook Marketplace', which is a specific verb+resource. However, it doesn't distinguish this from sibling search tools like search_vinted or search_tradera, relying on the name alone for differentiation.

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 provides strong usage context by warning that the tool is 'DISABLED BY DEFAULT', requires setting ENABLE_FACEBOOK_SEARCH=1, and implementing a stub. It also states that it returns an explanatory error otherwise. While it doesn't list alternative tools, the warnings clearly indicate when it cannot be used.

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