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

Annotations already cover read-only/idempotent safety, and the description adds genuinely new behavioral facts: billing is per page actually fetched with failed fetches free, and URLs are not logged. Those cost and privacy disclosures materially change how an agent should invoke it.

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?

Front-loaded scope constraint, then platforms, then exclusions, example, response, cost. Every clause carries information. The response-field enumeration is a dense run-on that would read better as a structured list, costing a point.

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?

Despite an output schema existing, the description adds cost model, privacy posture, failure behavior and scope limits — everything an agent needs to call this correctly. Nothing material is left unstated.

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 coverage is 100% with a single url parameter, so the schema does the heavy lifting (baseline 3). The description earns an extra point by giving a concrete example value, 'https://example.com', which pins down expected URL format.

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 names a specific verb and resource (find social-media profiles) and enumerates the platforms covered, so an agent knows exactly what comes back. It also scopes to homepage-only. It stops short of stating how this differs from the overlapping sibling extract_contacts, which also returns emails/phones per the response description.

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?

'Homepage only' and 'Share buttons are excluded' give clear usage boundaries and a negative case. What's missing is any named alternative — an agent cannot tell from this text when to prefer extract_contacts or extract_contacts_bulk over this tool.

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