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

Adds substantial behavior beyond the annotations: the data comes from a refreshed crawl rather than a live visit, 'last_checked' indicates scan time, small/new sites may show only partial stacks, and pricing is $0.05 per successful call with failed calls free. With readOnly/idempotent/openWorld already declared, this freshness, coverage, and cost disclosure is exactly the extra context an agent needs.

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?

Content is front-loaded: what the tool returns first, then use cases, then freshness caveats, then price. Sentences carry distinct information, though the dense enumeration of categories makes the opening clause long.

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?

An output schema exists so return fields need not be explained, and the description still covers data provenance, freshness caveats, partial-result risk, and cost. Nothing an agent needs to call this correctly is missing.

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 description coverage is 100%, and the schema itself documents both 'domain' (format and URL tolerance) and 'api_key' (when to leave empty). The description adds no additional parameter semantics, so the baseline 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 ('See what a website is built with') and enumerates the returned categories — store platform, CMS, email marketing, analytics, payments, hosting, plus contact/social data. This clearly separates it from siblings like domain_info or leads_by_tech, though no sibling is named explicitly to sharpen the contrast.

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?

Gives concrete usage contexts: 'qualify a sales lead, size up a competitor, or find out what software a company already pays for.' That is clear when-to-use guidance, but it offers no exclusions or named alternatives (e.g., when to prefer leads_by_tech or domain_info instead).

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