Facebook Marketplace listings

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

No annotations are provided, so the description bears full responsibility for behavioral disclosure. The description says nothing about what the tool does beyond returning 'structured data'—no mention of read-only nature, rate limits, authentication requirements, or output specifics. This provides zero transparency into the tool's behavior.

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 a single short fragment, but it is under-specified rather than appropriately concise. It omits essential information, so the brevity is not a virtue. The structure is just a noun phrase, not a clear instructional sentence.

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?

Given that the tool is a scraper-like utility for a specific website, the description is severely incomplete. It does not explain what fields are extracted, whether it expects a specific listing URL, or what the return format is. With no output schema and no behavioral notes, the agent lacks sufficient context to use the tool correctly.

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 input schema has 100% coverage with a single parameter 'url' clearly described as 'Facebook Marketplace listing URL'. The description adds nothing about the parameter, but the schema already provides adequate semantics, so the baseline of 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 description 'Structured Facebook Marketplace listing data' is essentially a restatement of the title 'Facebook Marketplace listings' with the addition of 'Structured' and 'data'. It does not state a specific verb or action (e.g., 'Retrieve' or 'Scrape'), so the tool's purpose is implied rather than explicit. This is close to a tautology and does not distinguish itself from sibling tools.

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 no guidance on when to use this tool versus alternatives. With a large list of sibling web_data_* tools for different platforms, the lack of any context, prerequisites, or alternative mentions leaves the agent without direction on selection.

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