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

Annotations already establish readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds material context the annotations cannot: a concrete billing rate ($0.008 per page), the presence of Facebook's AI content label (ai_label), and the optional date-range scoping. It leaves out pagination/cursor behavior, which is the only notable gap.

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?

Three compact sentences: what it does, what it returns, and how to narrow plus the cost. Front-loaded with the verb and resource, no filler. The return-field list is dense but each item is informative.

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 listing tool with full schema coverage and no output schema, the description covers operation, inputs, return contents and cost. Missing only pagination/volume expectations and explicit sibling routing, which keeps it short of 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 still adds value by tying page_id to its source endpoint (facebook_page_details) and by restating the per-page billing that governs the `pages` parameter, which the schema only says as "Billed per page" without a rate.

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 and resource ("Get posts from a Facebook page") and pins the identifier to a numeric page ID sourced from facebook_page_details. It also enumerates the returned fields. It never names the sibling it is not (facebook_group_posts, search_facebook_posts, facebook_page_details), so differentiation is left to inference.

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 by the required page_id and the optional date range, but there is no explicit when-to-use guidance and no pointer to sibling alternatives such as search_facebook_posts for keyword discovery. An agent must infer the selection rule.

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