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

The description carries the highest-value behavioral detail not present in annotations: it costs $0.001 USDC on Base per successful call via x402, and the per-successful-call phrasing implies failures are not billed. Annotations mark readOnlyHint=false, which would look inconsistent for a read tool, but the paid x402 settlement plausibly explains it, and destructiveHint=false / openWorldHint=true align with chain data reads. No contradiction, and useful context beyond 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?

Three tight sentences: output contents first, then purpose, then price — effectively front-loaded with the most useful identifying information. The field enumeration is a list, but each item is a distinct return value that would otherwise be unknown given the missing output schema.

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 compensates by enumerating return fields, and it discloses the payment mechanism and cost. The remaining gap is edge-case behavior — what is returned for a pending, dropped, or unknown hash — which matters for a receipt tool but is a minor omission for a single-parameter lookup.

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 (hash) and the schema documents it fully at 100% coverage, so baseline 3 applies. The description adds no format detail such as hash length, casing, or behavior on an unknown hash, but nothing is required given schema completeness.

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 names the specific resource (receipt of a Polygon PoS transaction) and enumerates what it returns: status, gas used, effective gas price, fee in POL, log count, contract created. This is far more specific than the vague siblings and distinguishes a receipt lookup from a raw transaction fetch, though it never explicitly contrasts itself with polygon_tx or polygon_logs.

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 to confirm a payment or call went through' implies the usage context, and the per-call pricing gives a cost-aware trigger. However no alternative is named — an agent choosing between polygon_receipt, polygon_tx, and polygon_logs gets no explicit routing rule, and there are no exclusions or failure-path guidance.

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