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

Annotations already declare readOnly and openWorld, but the description adds substantial context beyond them: the exact return shape (crawl id, URLs, status, mime type, timestamp) and a pricing/auth model ($0.05 USDC per successful call via x402, no API key). This is precisely the behavioral detail an agent needs to budget and invoke correctly.

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?

Three tight sentences: what it does first, then return values, then payment terms. No waste, and the primary definition 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?

With no output schema, the description compensates by describing the return contents. Single simple parameter, annotations cover the safety profile, and payment/auth context is included. An agent has everything needed to call and interpret it.

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 with 100% schema coverage, and the schema already documents that it accepts a domain, URL, or email address. The description adds nothing beyond restating 'on a domain', so the baseline of 3 applies.

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: enumerate every URL captured on a domain via public web crawls. This clearly distinguishes it from sibling tools like domain_emails, domain_ips, and domain_whois, and the 'passive ... without touching the site' framing removes ambiguity.

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?

Explains the use-case well: passive enumeration of a site's pages without touching the site, implicitly contrasting with active crawl siblings like http_get or http_screenshot. It stops short of naming those alternatives or stating explicit when-not conditions, so not a 5.

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