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

The description discloses a key behavioral trait beyond annotations: it may 'scan once only if none exists yet,' explaining why readOnlyHint is false. It also adds the `scanned_at` field so the agent can judge staleness, providing context that annotations alone do not convey. It doesn't go into error cases or rate limits, but for this tool the disclosed behavior is sufficient.

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 tightly packed: two sentences deliver purpose, behavior, return contents, staleness cue, and explicit alternative. Every clause earns its place, and the most important 'cheap read' framing is front-loaded.

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?

The tool has one parameter, a rich schema, and an output schema (though not shown). The description explains the full return face (the same seven-check report as scan_domain, including statuses and observed records) and provides the alternative guidance. There are no significant gaps for an agent to invoke it correctly.

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 input schema already provides 100% parameter coverage with a detailed description of the domain parameter including format rules and punycode normalization. The tool description does not add further parameter semantics, but it doesn't need to given the schema's richness. Baseline 3 is appropriate.

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 states the tool's verb and resource: 'Return the stored report for a domain.' It also distinguishes itself from the sibling 'scan_domain' by framing get_report as the 'cheap read' and 'right default for a first look,' while scan_domain is for forcing a fresh scan.

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?

Explicit usage guidance is provided: get_report is recommended as the default first look, while 'Prefer scan_domain when you specifically need state re-read right now — for example after a DNS change.' This directly tells the agent when to choose this tool over its alternate.

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