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

Annotations cover the read-only safety profile, and the description adds a real behavioral constraint: the read_insights permission gate and the specific time windows (28-day, recent posts) of the returned data. It does not clarify what happens when the permission is missing (error vs. partial payload), leaving one 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?

A single dense sentence that is front-loaded with the primary return value (follower count) and expands into the insight breakdown. Every clause carries information, though the parenthetical list makes it slightly heavy.

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 burden of describing returns, and it does so reasonably well by enumerating the metric categories. The main omission is the behavior when read_insights is not granted.

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% and both optional UUID parameters are documented in the schema itself. The description adds no syntax or default behavior beyond what the schema already provides, so 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 (Return) and resource (Facebook Page metrics), then enumerates exactly what is returned: follower count, engagement from recent posts, and 28-day Page Insights. This clearly distinguishes it from siblings like get_instagram_insights and get_youtube_channel_insights.

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 states a gating condition ('when the connection has granted read_insights'), which is a useful usage prerequisite. However, it never says when to choose this tool over the other platform-metrics siblings, nor what to do if the scope is absent.

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