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

The description discloses a key non-obvious behavior beyond the readOnlyHint annotation: reverse DNS is never run, only the command is returned. It also reveals that freshness information is included, giving the agent useful context about the data's reliability.

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?

Two dense sentences front-load the core purpose and the critical non-behavior. Every phrase contributes: what is returned, when to call it, and what it deliberately does not do.

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?

Even without an output schema, the description tells the agent exactly what to expect: per-crawler classification, source URLs or dig commands, and freshness. Combined with the readOnly and idempotent annotations, an agent has enough to invoke and interpret the result 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?

Schema coverage is 100% for the single optional 'crawler' parameter, so the schema already documents the accepted substrings and omission behavior. The description adds only 'per crawler' framing, which doesn't materially extend parameter meaning beyond the schema.

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 reports per-crawler verification methods: IP ranges, reverse DNS documentation, or none, along with source URLs or dig commands and freshness. It distinguishes itself from sibling tools by explicitly noting that reverse DNS is never executed here, clarifying its informational role.

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?

It gives an explicit trigger: 'Call it before reading anything into an address that matched nothing.' It does not name alternative tools directly, but the statement that reverse DNS commands are handed back rather than run implies when a real verification tool like verify_batch would be more appropriate.

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