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

Annotations already cover the safety profile (readOnly, openWorld, non-destructive), and the description goes further with information an agent cannot get elsewhere: exact cost ($0.008/page), the surcharge cost model for get_sentiment, the returned fields (author, engagement, media, ai_label), and the sort modes. Cost and return-content disclosure are exactly the behavioral context this dimension rewards.

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?

Four compact sentences, front-loaded with the action and identifier requirement, followed by return values, sort options, and pricing. No filler and nothing important buried.

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?

No output schema exists, and the description compensates by enumerating the returned data (post text, author, engagement, media, ai_label). Combined with cost and prerequisite guidance, an agent has everything needed to call this correctly against a 4-parameter schema.

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 beyond the schema by stating the per-page price ($0.008) where the schema only says 'Billed per page', and by surfacing the ai_label field that the sort/analysis parameters interact with.

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 public Facebook group') plus the exact identifier type required ('numeric group ID'), which cleanly separates it from facebook_group_details (metadata) and facebook_page_posts (pages, not groups). The scope qualifier 'public' is a meaningful distinguishing constraint.

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?

Tells the agent where to obtain the required input ('from facebook_group_details'), which is a concrete prerequisite that prevents a bad call. It does not, however, address when to prefer this over search_facebook_posts or what happens with private/closed groups beyond the 'public' hint.

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