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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds the credit cost ("(1 credit)"), which is genuinely useful operational context, but says nothing about behavior for private, deleted, or non-existent profiles, or about response shape beyond the field names.

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?

A single front-loaded fragment that wastes no words; the returned fields and credit cost are stated immediately. It is terse to the point of omitting routing and edge-case behavior, which caps it below a 5.

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 lookup with no output schema, enumerating the returned fields is exactly the right compensating detail, and the sole parameter is fully documented in the schema. Missing only failure-mode behavior for private or invalid profiles.

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 the url parameter already documents the accepted formats (profile URL, profile.php?id=, numeric id, Page name). The description adds no additional syntax, normalization, or format guidance, so the baseline of 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?

"Facebook profile or Page: name, avatar, followers, category" names the resource and enumerates the fields returned, so an agent can tell this fetches profile metadata rather than content. It does not explicitly distinguish itself from siblings like facebook_profile_posts or facebook_profile_photos, leaving that to inference from the field list.

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 implied rather than stated: an agent can infer this is the tool for account-level info (followers, category) rather than posts/photos. There is no explicit when-to-use, no exclusions, and no pointer to facebook_profile_posts/photos/videos as alternatives.

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