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

Annotations already declare read-only, non-destructive, open-world behavior. The description adds substantial context beyond those annotations: it discloses the $0.10 USDC x402 price, the bundled 'one call' nature, and the exact output format (grade plus findings and fix list). This gives the agent practical expectations about cost and result shape.

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 dense but every clause earns its place: what the report is, what it fuses, what the output is, when to use it, and what it costs. The structure front-loads the headline result and then provides needed supporting detail.

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?

There is no output schema, so the description must explain what the agent will receive; it does, naming the three health levels, the graded output, and the consolidated findings/fix list. Combined with the single required parameter, use cases, and pricing, the agent has enough context to call this tool 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 covers the only parameter, domain, with an adequate description. The tool description also names 'domain' as the subject but adds no syntax, format, or edge-case meaning beyond the schema. Baseline 3 applies because schema coverage is 100%.

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 precise, differentiated function: it produces a bundled domain threat report with HEALTHY/NEEDS_ATTENTION/HIGH_RISK grades, fusing DNS and email hardening signals into one grade plus findings. This clearly distinguishes it from narrower sibling tools like dns_lookup or security_threat_lookup, and it names the concrete technical inputs (SPF, DMARC, DNSSEC, CAA, nameservers).

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?

The description identifies clear use cases — security, diligence, and vendor review — which tells an agent when to select it. It does not explicitly state when not to use it or name alternatives, so it stops short of full routing guidance.

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