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

With no annotations at all, the description carries the full burden and does a strong job: it discloses the 2-credit cost, free handling of empty results and failures, 24-hour cache behavior, and the approximate-count/failure/skip response characteristics. This is far more than a generic read-only statement.

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?

The description is compact, front-loaded with the core resource, and every sentence adds value: response characteristics, cost, failure policy, and cache behavior. No filler or repetition.

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 tool with no output schema, the description does a reasonable job of hinting at response content via listingHits/hydrateFailures/hydrateSkipped and approximate counts, plus the required url parameter is documented in the schema. It could more clearly state the overall return shape, but the core calling and billing context is complete.

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%, so the baseline is 3. The description mentions cache, sortBy, and approximate counts, but it mostly echoes or lightly references what the schema already documents rather than adding new parameter-level meaning.

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 identifies the resource as 'Public Facebook group posts' and lists the notable response attributes, so an agent can tell this is a fetch/list operation for group posts. It is specific enough to distinguish from profile posts or page details, though it lacks an explicit verb like 'get' or '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?

The description clearly implies it is for public Facebook group posts, but it never names sibling tools or conditions for when to choose this over, for example, facebook_profile_posts or facebook_page_details. It does provide useful operational guidance on caching and credit charges, but 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.