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

Annotations cover the safety profile (readOnly, idempotent, no open-world access), and the description adds material context beyond them: the call is metered at USD 0.01 per call payable in USDC on Base via x402, or via an X-API-Key Commercial key. That payment/auth requirement is exactly the kind of behavioral detail an agent needs before invoking.

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?

Two sentences: the first front-loads what the tool returns, the second carries the billing/auth mechanics. No filler or redundancy, though the pricing clause could be split more cleanly from the purpose statement.

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 names the main return fields (contact, end dates, amounts), and it discloses the payment requirement. For a read-only filtered-list tool this is nearly sufficient; pagination and exact record shape are left implicit.

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%, so the schema already explains id, page, buyer, country, and ends_before in detail. The description adds no syntax or constraint information beyond echoing the returnable fields, so the 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/resource: contract rows for one line of business, with the fields returned (contact, end dates, amounts). It is distinguishable from siblings like assay_contract or assay_line, though it does not explicitly say how it differs from them.

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 never states when to use this tool versus assay_contract, assay_line, or assay_supplier_contracts. Usage is only inferable from the name and the required (country, id) pair, which mirrors assay_search output.

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