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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the read-only nature is established. The description adds that it is 'Free' and lists the returned components, but it does not explain behaviors like what happens when no unpaid offer exists or whether external calls are made. With annotations covering the safety profile, the bar is lower, and the description adds some context (free, return fields) but not rich behavioral detail.

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 a single sentence, front-loaded with 'Free', and packs the essential information (what is returned and its components) without fluff. The phrase 'for a check' is somewhat ambiguous and could be clearer, but overall it is appropriately terse and well-structured.

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 simple read-only tool with two parameters and no output schema, the description is mostly sufficient: it names the return fields and the annotations cover safety. However, it leaves 'check' undefined and does not mention edge cases (e.g., missing chain, unsupported address, no unpaid offer). Given the tool's simplicity, this is a minor gap but still leaves room for ambiguity.

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 50% (chain has no description; address does). The description says 'networks' plural and 'for a check' but does not clearly map the chain parameter to networks or explain how address affects the quote. It fails to compensate for the missing chain description, leaving the agent to infer parameter semantics from enum values and the address description alone.

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 states a specific verb ('Returns') and a concrete resource ('the unpaid HTTP 402 offer') and lists the exact fields returned (networks, USDC amount, payTo, raw PAYMENT-REQUIRED). It is clearly distinct from sibling tools like get_sample_report or token safety checks, so an agent can identify it immediately.

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 gives no explicit guidance on when to use this tool versus the sibling tools. It does not mention alternatives, prerequisites, or conditions under which the quote would be unavailable. The word 'Free' hints at a reason to use it, but that is not enough to guide selection.

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