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

Annotations only say readOnly and openWorld; the description adds materially important behavior: traffic goes through a residential proxy, each successful call costs $0.01 USDC via x402 on Base/Solana/Arc, and failed calls are not charged. Cost and payment prerequisites are exactly what an agent needs before invoking a paid tool.

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?

Purpose, source and coverage caveat are front-loaded, followed by pricing. It's dense but readable; the enumeration of return fields (profile id, rank, name, link, photo) is partially redundant with the output schema and is the one place trimming is possible.

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?

For a one-parameter read-only search with an output schema and readOnly/openWorld annotations, everything an agent needs is present: data source, coverage limits, cost model, payment rails, and failure-billing policy. The output schema covers return values, so no gap remains.

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?

Only one parameter and schema coverage is 100%, so the baseline is 3. The description adds modest value by mapping the name to the /public/<name> URL form, but it doesn't specify formatting rules (spaces vs. hyphens, full name required, middle names) beyond the schema's 'John Smith' example.

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 and resource (people search by name on Facebook's public people directory) plus the exact URL pattern facebook.com/public/<name>, the logged-out view and the ~24 result cap. This distinguishes it cleanly from siblings like social_facebook_pages, social_facebook_posts and social_instagram_profile.

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?

It gives clear qualifying context for when this tool works — logged-out public directory, only profiles whose owners allow public search, capped at ~24 results — which tells an agent when the tool will return empty or partial data. It stops short of naming an alternative (e.g. social_contact_info or social_facebook_pages) for cases outside the public directory.

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