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

With no annotations, the description must carry the behavioral burden. It discloses the full scope of checks and the $0.003 USD / x402 cost, which is useful operational context, but says nothing about permissions, rate limits, or whether results include raw record data versus verdicts.

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?

A single front-loaded sentence that lists the analysis scope and appends the price without filler. Every clause carries information.

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 one-parameter, read-only analysis tool with no output schema, the description gives an adequate picture of what is inspected and what it costs. It would be fully complete with a note on prerequisites (e.g., domain must be publicly resolvable) or the shape of the result.

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?

Only one parameter ('domain') exists and schema coverage is 100%, so the schema fully documents it. The description adds no syntax, format, or validation detail beyond the schema, making the baseline 3 correct.

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 ('Analyzes') and enumerates the resources examined (DNS zone records, SPF, DMARC, mail connectivity), so the agent knows this is an email-authentication-focused DNS check. It does not explicitly differentiate from close siblings like check_dns_and_headers or run_dns_snapshot_check, so it stops short of a 5.

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 never states when to use this tool versus the many DNS-adjacent siblings, nor any prerequisites or exclusions. The only contextual note is a price, which is not usage guidance.

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