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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive, so the safety profile is covered. The description adds meaningful behavioral context by noting the data is from the latest full scan, implying a snapshot that may not reflect live state, and by enumerating the included metric categories. It does not describe the exact response shape, but the annotations lower the burden.

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?

The description is a single sentence with a colon-delimited list of content categories. It is front-loaded with the core purpose and contains no filler or redundant restatement of the tool name.

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 parameterless, read-only stats tool, the description covers the main output dimensions and the snapshot timing. Since there is no output schema, it could list exact field names, but the categories given are enough for an agent to understand what results to expect.

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?

The tool has zero parameters and the schema has no properties, so there is no parameter semantics for the description to clarify. The baseline of 4 for a parameterless tool applies, and the description correctly avoids inventing parameter details.

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 clearly identifies the resource and scope: catalogue-wide size and health metrics including resources, hosts, verdict counts, and payable endpoints. It lacks an explicit verb like 'returns' or 'reports', but the noun-phrase framing plus the metric list makes the purpose unambiguous. It also distinguishes itself from sibling tools by emphasizing the whole-catalogue view rather than host, endpoint, or payability specifics.

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?

No guidance is given about when to use this tool versus alternatives such as reports, host_summary, or payability_verdict. The phrase 'as of the latest full scan' hints at snapshot semantics, but there is no explicit when-to-use, when-not-to-use, or pointer to sibling tools.

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