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

Annotations already cover safety (readOnlyHint=true, destructiveHint=false, openWorldHint=true), and the description adds genuinely useful behavior beyond them: a hard 3-post-per-page API cap, credit costs, repurchase on repeated requests, and the unusual nullable-boolean semantics of is_paid_partnership (never false, null means unknown). That nullability caveat is exactly the kind of trap an agent could misread as 'not sponsored'. It loses a point because the cost statements are internally inconsistent ('at least 10 Nexscope credits' vs. '1 credit per request'), which will confuse budgeting.

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 core description is printed twice nearly verbatim, and the middle is contaminated with scraped page chrome ('Facebook Profile Posts API View Pricing', '1 credit per request'). Front-loading is decent in the first sentence, but roughly half the text is redundant or non-instructional, so it fails to earn its length.

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 no output schema, the description carries the return-value burden and does so well: it enumerates post fields, link_attachment contents, video details, and null-field behavior. Cost is disclosed (albeit inconsistently) and the url-or-pageId requirement is stated. The remaining gap is the all-optional parameter set — an agent is not told what happens when no identifier is passed or how cursor interacts with the identifier.

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 description coverage is 100%, so the schema already defines url, pageId, and cursor, making 3 the baseline. The description adds one real signal — pageId is faster than url — but says nothing about the cursor parameter despite the 3-per-page pagination model, and does not address what happens when neither url nor pageId is supplied even though the schema marks all three parameters optional.

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 opening sentence gives a specific verb and resource — 'Returns publicly visible Facebook profile posts' — plus the 3-per-page constraint, which is enough to distinguish it from single-post tools like social_facebook_post. However, it never names the nearest siblings (social_facebook_group_posts, social_facebook_profile_photos, social_facebook_profile_reels) to draw the boundary explicitly, so the differentiation is inferred from the resource noun rather than stated.

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 only routing guidance is parameter-level: 'Accepts either a url or pageId parameter, where pageId is faster.' There is no statement of when to prefer this tool over the group-posts or profile-photos siblings, and no exclusion cases. Usage is implied by the resource rather than explained.

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