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

Annotations already declare readOnlyHint and openWorldHint; the description adds valuable context: credit cost, field mappings into followerCount/category, and the fact that member counts may be rounded with raw.memberCountIsApproximate. It stops short of failure/privacy behavior and cache semantics.

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?

It is front-loaded with 'Public group info' and then spends its sentences on useful output mappings and cost, not filler. It is appropriately sized for a no-output-schema tool.

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 simple read-only lookup with annotations and an input schema, the description covers the key returned fields, the rounding quirk, and cost. It is only incomplete on cache behavior and non-public/error cases.

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?

The schema documents url but not cache_max_age, and the description contains no input-parameter guidance at all. With 50% schema coverage, the opaque cache_max_age parameter is not compensated for by the description.

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 states a specific resource and enumerates the fields returned (name, member count, privacy setting, description) and restricts it to public Facebook groups. That is enough to distinguish it from facebook_groupPosts and other Facebook profile/page tools.

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 establishes the scope (public groups) but gives no explicit when-to-use guidance, prerequisites, or named alternatives such as facebook_groupPosts for posts. Usage is only implied by the purpose.

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