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

Annotations already declare this a free read (readOnly, idempotent, non-destructive, openWorld), so the safety profile is covered. The description adds genuine context beyond the annotations: that the sponsor itself is priced from $0.03, that it has price rules and lanes, and which chains are supported.

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?

A single dense sentence (preceded by 'Free.') covering use case, mechanism, price and chains with no filler. Front-loading is slightly off, since 'Free.' leads rather than the core subject, but overall it is efficient.

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?

Because an output schema exists, return-value details need not be repeated, and the description covers chains, the USDC-only scenario, pricing and lanes. For a parameterless info tool it is largely complete, though it could name how it relates to the bridge/x402 siblings.

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 tool takes zero parameters, which is the baseline-4 case, and schema description coverage is 100%. The description introduces no parameter concepts that need explaining, so nothing is missing here.

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 makes clear this is an informational tool about the x402 gas sponsor: what it is, how it lets a USDC-only wallet transact on Base/Polygon/Solana, plus its price rule and lanes. The purpose is specific and the resource is named, but there is no explicit verb ('get/read info') and no differentiation from informational siblings such as liquid_guide or payment_readiness.

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?

Usage is implied via the scenario it addresses ('a wallet that holds USDC but no ETH/POL/SOL'), which tells the agent when the info is relevant. However, there is no explicit when-to-use/when-not framing and no named alternative tool, so the agent must infer routing.

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