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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is largely covered; the description reinforces it ('no domain mutation, no destructive side effects') and adds non-schema facts: the ~3-8s runtime, 'No auth', and the shape of the response. It does not discuss rate limits or failure modes, so it stops short of a 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?

Front-loads the core action, timing, and return payload, then moves to routing and follow-ups. It is dense but every clause carries information; the return-payload enumeration is slightly list-heavy but still earns its place given no output schema.

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 and only one parameter, the description carries the burden well: it enumerates return contents (letter grade, numeric score, issue list, recommendations, result sections, citation URLs), notes the runtime and auth requirements, and points to alternatives and follow-up tools.

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?

Single parameter with 100% schema description coverage, so the schema already explains 'domain name only, no URL, path, or port'. The description adds no further parameter syntax or format guidance, making the baseline 3 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?

States a specific verb and resource ('Run the fast IntoDNS.ai DNS and email security scan'), gives the runtime, and enumerates the deliverables (grade, score, issues, recommendations, citation URLs). It explicitly contrasts itself with get_everything_report and start_deep_scan, so the agent can distinguish it from siblings without opening schemas.

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?

States it is 'the default tool for agent-visible scan evidence' and names the conditions selecting alternatives: get_everything_report for deeper single-shot reporting, start_deep_scan for slower Internet.nl-grade analysis. It also routes post-scan follow-up to explain_issue and generate_dns_fix.

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