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

Annotations only declare readOnly and openWorld, but the description goes well beyond them: it discloses the paid x402/Base pricing at $0.03 USDC per result, the exact charging condition (only when at least two of three checks return data), and that the call consumes one of 5 free daily calls. It also explains the tri-state result semantics (found/not_found/unknown with underlying data).

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?

One front-loaded paragraph that leads with what the tool does before pricing and caveats; every clause carries information. Slightly dense with billing detail, but none of it is filler for an agent that must decide whether to spend a call.

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 an output schema present, the description needn't enumerate return values, and it already explains the tri-state signal model and the facts-only boundary. The one real gap is that it gives no hint about when to prefer the nearly identical sibling company_footprint_check.

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% and the single domain parameter is fully documented in the schema, including format constraints and an example. The description only adds the framing "for one domain," so the schema does the heavy lifting; 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: for one domain it reports which public operating signals exist (ad/analytics tags, job board, Google Ads Transparency), and it explicitly bounds the scope with "Facts only: no revenue, burn or fraud estimates." However, the tool name says "legitimacy and security" while the description delivers a factual footprint check, and it never distinguishes itself from the near-duplicate sibling company_footprint_check.

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 names the intended audience ("investment, due-diligence and vendor-risk agents"), which implies the use case. But there is no explicit when-not guidance and no routing to overlapping siblings such as company_footprint_check, get_google_ads_by_domain, get_company_open_jobs or detect_website_tech_stack, which cover the same individual signals.

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