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

Annotations already declare read-only, idempotent, non-destructive, open-world, but the description adds information annotations cannot carry: cost ($0.03 USDC via x402 v2 on Base), the required PAYMENT-SIGNATURE header and endpoint, and the billing guarantee 'No website found = no charge'. Pricing and failure-billing behavior are exactly the traits an agent needs before invoking a paid tool.

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?

The description is front-loaded with the value proposition, then output shape, then inputs, then payment mechanics — a sensible order with no filler sentences. It is dense but slightly overloaded, bundling endpoint URL and payment protocol detail into the same block as the semantic description.

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 does the work of describing return values (verdict, score, reasons, opening line), and it covers the nested 'for' object and pricing/auth model. The gap is the four unexplained auxiliary parameters (city, country, lang, official_checks) on a fairly complex nested-schema tool, which an agent may need to set 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 description coverage is only 14%, so the description has to compensate. It does document the core inputs (domain or name, and the 'for' object with seller, goal enum values, optional ideal_customer), but leaves city, country, lang, and official_checks entirely unexplained in both schema and description. That is meaningful but partial compensation for a 7-parameter tool.

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 opening sentence names the exact decision the tool answers ('Is this company worth contacting FOR YOU?') and quantifies the deliverable: verdict (good/maybe/poor), 0-100 score, fact-grounded reasons, and an opening line. It explicitly positions itself against the sibling company_enrich ('Everything in company-enrich, plus a fit verdict'), so an agent can choose between the two without inspecting schemas.

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 framing 'Is this company worth contacting FOR YOU?' plus the required 'for' payload makes the use case clear: personalized outreach qualification rather than generic enrichment. It also implies the alternative (company_enrich) for plain data. It lacks an explicit 'do not use when you only need raw company data / no seller context' exclusion, so it stops just short of 5.

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