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

Annotations already cover read-only, non-destructive, open-world and non-idempotent behavior, so the description's added value is in disclosure of what is returned (post text, URLs, dates, group title, reaction/comment/share counts) and what is not (profiles, nested comments). The payment-chain caveat ('not offered on Solana: pay on Base or Polygon') is an unusual but genuinely useful operational constraint an agent can't get from annotations.

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?

Five short sentences, front-loaded with purpose, then output contents, use case, exclusions and the payment caveat. Each sentence carries information, though the payment-chain note sits awkwardly at the end without a lead-in.

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 correctly takes on the job of describing return contents and explicitly lists what is absent. Combined with a fully documented two-parameter schema and complete annotations, an agent has what it needs to call this correctly; only explicit sibling routing is missing.

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 the schema itself documents the url format plus the limit range, default, clamping behavior and quote reporting. The description adds no parameter-level meaning beyond that, so the baseline of 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?

The description opens with a specific verb+resource: 'Read recent posts from one public Facebook group,' and scopes it to public groups only. That is enough to separate it from facebook-comments (nested comments explicitly excluded) and broadly from facebook-posts/facebook-page, though it never names those siblings directly.

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?

It gives a use case ('research recurring questions and discussion topics') and a negative scope boundary ('member profiles and nested comments are not returned'), which implies facebook-comments is the tool for threaded replies. However, there is no explicit when-to-use / when-not-to-use versus facebook-posts or facebook-page, so the agent must infer the routing.

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