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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds real behavioral context on top: the currency code is the issuer's claim, not attested backing; pricing is $0.03 per call over x402 on Base; a prepaid x-credit-token header unlocks unlimited calls; there is no free tier and no API key. These auth/payment and trust caveats are exactly the disclosure that helps an agent invoke correctly.

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 core purpose is front-loaded in the opening clause, and the sentences largely earn their place (the caveat and pricing details are actionable). The single em-dash-heavy paragraph is dense but not padded.

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?

An output schema exists, so return values need not be explained, and annotations carry the safety profile. The description still covers the trust caveat, payment/auth requirements, and the required input, leaving nothing essential for a correct call missing.

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 coverage is 100% for the single address parameter, so the schema already documents it fully. The description only restates 'Required input: address' and adds no syntax or format detail beyond the schema, making the baseline 3 appropriate.

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 and resource: reads the declared peg currency alongside issuance (supply, cap) and control powers (seize/freeze/pause/uncapped-mint), summarized as a one-call 'what is this stablecoin and who controls it'. The composite scope is clear, but it does not explicitly distinguish itself from close siblings like b20_peg, b20_supply, or b20_control, so an agent must infer the difference.

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?

Offers a usage context ('for agents settling in B20 stablecoins') but no explicit when-to-use-vs-alternatives guidance. It never says when to prefer this composite call over the narrower b20_peg / b20_supply / b20_control siblings, leaving routing to inference.

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