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

Beyond the readOnly/idempotent annotations, the description discloses non-obvious operational behavior: the $0.03 per-call price, the x402/USDC on Base payment rail, and that the endpoint returns payment requirements unless a payment_signature is supplied. This payment handshake is exactly the kind of trait an agent must know before invoking the 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?

Three tight sentences covering purpose, usage, and payment mechanics, with the core value proposition front-loaded. Nothing is wasted, though the payment and sample pointers make it slightly dense.

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 7-parameter, no-output-schema tool, the description covers purpose, use cases, and the critical payment flow. It does not describe the shape of the returned award records beyond a sample path, but with annotations and a full schema it is nearly complete.

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% across all 7 parameters, so the schema already carries the parameter documentation burden. The description adds no filter syntax, default values, or format detail beyond what the schema states, 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?

The description gives a specific verb and resource ('Find out who wins EU public contracts') and tags the domain [Procurement]. It implies the distinction from search_tenders by focusing on award winners rather than open opportunities, but it never names that sibling explicitly, so differentiation is left partly to inference.

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?

'Use when sizing a public-sector market or researching a competitor's contracts' states concrete use cases rather than a vague purpose. However, it offers no exclusions or alternative routing (e.g., when to prefer search_tenders or tender_alerts), so it stops short of full when/when-not guidance.

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