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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the description's real contribution is the credit cost — '15 points per returned record' — which is billing behavior found nowhere in the structured fields. It also enumerates returned fields in lieu of an output schema. It stops short of noting failure modes for unresolvable pages or rate limits.

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?

Two sentences, zero filler: the first front-loads the resource and the returned field list, the second delivers the cost. Nothing is repeated from the schema or annotations.

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?

With no output schema, enumerating return fields and the per-record cost makes the definition actionable for a single-record lookup. What is missing is minor but real: no note on what happens when a page cannot be resolved, and no hint that the language parameter changes which localized page variant is scraped.

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%: both url and the large language enum are fully documented in the schema, including an example URL and the default en-US. The description's 'URL, name or ID' reinforces the url parameter but adds no format or semantic detail beyond it, so the baseline 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 names the specific resource (Facebook pages) and enumerates exactly what is returned — email, phone, websites, address, categories, likes, followers, rating, creation date — plus the accepted identifier forms. It does not explicitly contrast with the sibling run_facebook_pages, so an agent must infer that this is the contact-focused variant, but the 'contacts' framing is clear.

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?

Usage is only implied: 'by URL, name or ID' tells the agent what input to supply, but there is no statement of when to pick this over run_facebook_pages or run_facebook_search, and no exclusions or prerequisites. An agent can guess the intended case (needs contact/outreach data for one known page) but is not told.

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