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

Annotations already cover the safety profile (readOnly, non-destructive, open-world). The description adds genuinely useful behavior: the feed is walked three posts per request via pagination.nextPageToken and each request is billed separately. It stops short of describing failure modes or rate limits, so a 4 rather than 5.

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?

Purpose is front-loaded, then return fields, then pagination, then use cases. The long comma-delimited enumeration of returned fields is dense but each item is informative; it borders on oversized but nothing is truly wasted.

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 full burden of explaining return values, and it does so thoroughly — listing all key fields, the nested post structure, and pagination semantics. An agent has everything needed to call and interpret results.

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 the schema already documents handle formats, the language enum's effect on localized strings, and the pagination token. The description only restates the pagination walk, adding no syntax or edge-case detail beyond the schema. Baseline 3 applies when the schema carries the load.

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 states a specific verb and resource ('Fetches a public Facebook page or profile by handle') and enumerates the concrete return contents (page id, name, category, likes, followers, posts). An agent knows exactly what it retrieves and at what granularity, with no ambiguity from a sibling set (none exist).

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 explicit use contexts — enrich company/creator records, verify brand reach and contact details before outreach, monitor competitors, build datasets. It does not name when *not* to use it, though the schema does note groups and private accounts are unsupported. Clear context, but no exclusion guidance in the description itself.

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