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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the description doesn't need to repeat safety. It adds valuable behavioral context: newest-first ordering, three posts per page, the specific fields returned (text, reaction/comment/share counts, timestamp), cursor-based pagination, and a credit cost. The only minor gap is lack of auth or error-behavior details.

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 four short sentences, front-loaded with the core purpose, then the return details, pagination hint, and cost. Every sentence earns its place with no redundancy or filler.

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 read-only, open-world tool with no output schema, the description covers the essential return data, pagination, and cost. It doesn't explain cache_max_age or mention rate limiting beyond cost, but those are minor omissions given the overall clarity and the annotations already covering safety.

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 67% (2 of 3 parameters described). The description reinforces the cursor semantics ('Pass pagination.cursor back for the next three') and ties it to the page size, but it adds no extra meaning for the url parameter beyond its schema description and completely omits cache_max_age. This is adequate but leaves gaps.

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 (retrieves) and resource (public posts from a Facebook Page), and lists the returned fields. It implicitly distinguishes Page posts from group or profile posts via 'from a Facebook Page', but it never names a sibling tool as an alternative, so it falls short of 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?

The description implies when to use the tool ('Recent public posts from a Facebook Page'), but it gives no explicit when-not conditions or alternatives—such as directing group posts to facebook_groupPosts. The pagination instruction ('Pass pagination.cursor back') is usage guidance for repeat calls, not for tool selection.

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