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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is covered. The description adds meaningful non-annotation context: the pricing model (ceil(posts_returned / 3) credits, minimum 1) and that pagination/time filtering are supported, which an agent needs to budget and call correctly.

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?

Two tight sentences with the purpose front-loaded and pricing appended as a secondary concern. Nothing is wasted, though the pricing sentence could be marginally more compact.

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, output-schema-backed tool this is nearly complete: purpose, filtering scope, and cost are all covered, and return values need not be described since an output schema exists. The only real gap is routing guidance versus the group/search post siblings.

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 all six parameters (including link, limit, cursor, and time bounds) are already documented with types, defaults, and ranges. The description gestures at pagination and time filtering but adds no syntax beyond the schema, so the baseline 3 applies.

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 recent posts from a Facebook page') and its scope (pagination and time filtering), which distinguishes it from facebook_get_group_posts and the search posts tools. It stops short of explicitly naming the sibling it is not, so sibling 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?

The page scope implies when this tool applies, but there is no explicit when-to-use or when-not-to-use guidance and no mention of the obvious alternatives (facebook_get_group_posts, facebook_search_posts). Usage is inferable from the subject but not stated.

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