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

Annotations already declare readOnlyHint/openWorldHint/idempotentHint, but the description adds substantial context they cannot carry: the $0.0027 x402 price, that the 402 challenge is free, that failures return >=400 and are not charged, and that a failed-after-payment call settles nothing. This is exactly the billing/settlement behavior an agent needs before spending money.

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 purpose and the returned fields are front-loaded in the opening clause, and every section (chains, defaults, payment, errors) carries real information. It is dense and the payment detail sits mid-paragraph, but the length is justified by the tool's paid, multi-step nature.

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 paid tool with an output schema and full annotation coverage, the description supplies everything the agent needs: what is returned, which chains, the default, the 402/payment handshake, and the error/charging policy. Nothing required to call it correctly is 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 description coverage is 100%, so the schema already documents chain, token, and payment thoroughly, including the two-call payment flow. The description largely restates that (Base default, no body = USDC on Base), adding little beyond what the structured fields provide, so the 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+resource ('Who holds an ERC-20') and enumerates exactly what it returns: top 10 holders with share of supply and contract/locked/burn status, LP holders and locked LP, creator/owner share, holder count, and raw vs controlled concentration. This content is clearly distinct from siblings like token_price, token_metadata, and token_safety, so an agent can route without opening the schema.

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 clear operating context: Base is the default chain with six alternatives, omitting the body returns USDC on Base, and the payment flow is spelled out (first call yields a 402 challenge, second call pays). It stops short of explicitly contrasting when to choose this tool over token_report or token_safety, so no true when-not guidance.

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