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

Beyond the annotations, the description discloses important behavioral traits: source records are not modified, a successful paid invocation can consume x402 payment, the payment-required challenge is free, repeating the tool may require a new payment, and matching quality depends on the source. This is exactly the kind of context that annotations alone do not provide.

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 longer than average but each section—purpose, use/avoid, limitations, price, paid-call behavior, networks—serves a distinct decision-making purpose. The core purpose is front-loaded, and the label-based structure makes it scannable. A small amount of redundancy with the schema keeps it from a 5.

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?

For a paid search tool with side effects, the description covers all essential context: when to use it, when not to, limitations of the result set, pricing, payment behavior, and accepted networks. Since an output schema exists, return-value details need not be spelled out. Nothing an agent needs to safely invoke this tool 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?

The input schema already provides complete descriptions for all three parameters (query, limit, postal_code), so the description adds little new semantic detail. It does summarize the query types and optional location criteria, but that information is already present in the schema.

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 description opens with a specific verb and resource: 'Searches French companies by name, SIREN, SIRET or optional location criteria and returns structured matching company records.' It also distinguishes itself from sibling tools by positioning this as the candidate-finding step rather than a verification or intelligence endpoint.

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 description provides explicit 'Use when' and 'Avoid when' guidance, naming the exact alternative endpoints (company/fr/verify, company/fr/intelligence) and the conditions that should route an agent to them. This leaves no ambiguity about when to select this tool.

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