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

Annotations already declare readOnly/openWorld/non-destructive, so the description is not obligated to restate safety. It usefully adds that exact_followers_count triggers a deeper scrape and that calls cost 1 or 5 credits, which is real behavioral information an agent should weigh before invoking.

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 padding, with the capability statement front-loaded and the cost caveat immediately after. Every clause earns its place.

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 an output schema present, return values need not be explained, and both params are covered. What is missing is the relationship to adjacent tools (page ID resolution, page search) and any prerequisite that the input must be a full page URL rather than an ID.

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% and both parameters (including the default for exact_followers_count) are fully documented in the schema. The description only restates the pricing already present in the parameter description, adding no new syntax or format meaning, 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?

States a specific verb and resource (get details about a Facebook page) and enumerates the fields surfaced (followers, contact info, category), so the agent knows what comes back. It does not differentiate itself from near-siblings like facebook_get_page_id or facebook_search_pages, which is the only thing holding it below a 5.

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?

No when-to-use guidance and no routing versus alternatives such as facebook_get_page_id (resolve URL to ID) or facebook_search_pages. The only decision aid is the cost tradeoff for exact_followers_count, which is a parameter choice, not tool selection guidance.

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