v1_facebook_marketplace_item

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

Discloses stub endpoint returning mock data until live scraper ships, and includes safety warning about not acting on responses. No annotations provided, so description carries full burden and excels.

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?

Four concise sentences, each adding value. Front-loaded with purpose, then technical details, then safety warning. No wasted words.

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?

Adequately covers purpose, parameter requirements, stub behavior, and safety. Lacks output format description, but acceptable for a simple get tool with no output schema.

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 descriptions already explain id and url as any-of group. Description adds clarity that at least one must be supplied, adding value beyond schema.

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?

Clearly states 'Get a single Facebook Marketplace item by URL/id', specifying action, resource, and identifier method. Distinguishes from sibling tool v1_facebook_marketplace_search which is a search tool.

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?

Requires one of url or id, and mentions call details (GET endpoint, cost). However, no explicit guidance on when to use this vs alternatives like search or location search.

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