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

Annotations only cover readOnly/openWorld, but the description discloses a full behavioral profile: $0.002 USDC per call via x402, failed calls are free, the quote-then-pay handshake, and a free tier of three calls per day without a wallet. This is exactly the kind of cost/auth/rate context annotations cannot express.

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 tight paragraphs, front-loaded with the capability and return fields before the payment mechanics. Every sentence carries information; the only minor cost is that the pricing block is dense, but it is genuinely necessary detail.

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 steps in by enumerating the returned fields and the chain-specific extras (Solana mint/freeze authority). The payment lifecycle and free-tier carve-out are fully spelled out, leaving nothing an agent needs to invoke it correctly.

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 documents `chain` (with enum and default), `token` (ERC-20 contract vs SPL mint), and `payment`. The description restates the chains and mentions the quote flow but adds no syntax or format detail beyond the schema, so 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 (look up) and resource (token) across three named chains, and enumerates the exact returned fields (name, symbol, decimals, total supply, mint/freeze authority on Solana), which cleanly separates it from the pricing-oriented token_price sibling. It never names token_check or token_price explicitly, so the differentiation is inferred from content rather than stated.

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?

Gives a clear use case ('confirm what an address actually is before acting on it') and a concrete invocation protocol: call without `payment` for a quote, then sign and re-call. It does not state when to prefer this over token_check or token_price, so no explicit exclusions are offered.

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