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

Annotations only declare readOnlyHint and openWorldHint, but the description adds substantial behavior: per-result cost ($0.03 USDC via x402 on Base), the conditional billing rule tied to data availability, and that it consumes one of 5 free daily calls. This is exactly the kind of pricing, billing, and quota context the agent needs and cannot get from structured fields.

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?

Front-loaded with the core capability, then usage, then cost and billing rules. Every sentence carries distinct information (capabilities, use case, pricing, charging condition, quota) with no redundancy.

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 values need not be explained; the description still summarizes the returned 'plain-language signals'. Combined with the pricing, billing, and quota disclosures, 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?

Only one parameter (domain) with 100% schema description coverage, and the schema already specifies format constraints ('without a URL scheme, path or port') and an example. The description adds no additional parameter-level meaning, 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+resource ('Company enrichment API in one call') and enumerates exactly what it aggregates: tech stack lookup, hiring signals and buying intent, and Google Ads transparency. It distinguishes itself from siblings by being the combined 'one request instead of three' version of detect_website_tech_stack, get_company_hiring_intent, and get_google_ads_by_domain.

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?

Explicitly gives the use case ('a full company research profile before outreach') and contrasts with the alternative of three separate requests. The charging rule ('charged only when at least two of the three sections have data; otherwise nothing is charged and the answer says which single tool has data') further routes the agent toward the single-section sibling tools when only one section applies.

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