List top x402 sellers

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

Annotations already convey readOnly, idempotent, and non-destructive behavior. The description adds significant behavioral context beyond that: the data is 'derived from on-chain USDC transfers,' time windows ('last ~24h', 'rolling 7d/30d'), network specifics (Base, Tempo), and that it is free to call with no payment or proof-of-work. It also documents defaults, including excluding the service's own wallet.

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 description is dense but every sentence earns its place: the first sentence states the core function, the second and third explain the two modes, the fourth gives the use case, and the fifth covers cost and defaults. There is no fluff or redundant restating of the tool name.

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?

Given that an output schema exists, the description does not need to spell out return fields. It covers the key operational aspects an agent needs: what each mode returns, the networks involved, time windows, defaults, and the fact that it is free. This is complete for a read-only leaderboard listing tool.

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 baseline is 3. The description goes beyond the schema by explaining the meaning of each wire mode ('wire=x402 (default): x402 sellers earning the most USDC... wire=mpp: MPP sellers ranked by inbound USDC.e transfers on Tempo') and clarifying the sort semantics in context. This adds worthwhile semantic context rather than merely restating parameter names.

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 opens with a specific action and resource: 'List ranked sellers from the on-chain leaderboards.' It then clearly distinguishes the two modes (x402 and mpp), including what each ranks and on which network. This makes it unmistakably different from the sibling general-purpose tools.

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?

The description provides a clear use case: 'Useful for agents discovering the live x402 / MPP economy: who's getting paid, which networks, and where to point demand.' It also states that the call is free, which is relevant for an agent deciding whether to invoke it. It does not explicitly mention when not to use the tool or name alternatives, but no sibling tool is a true alternative for this leaderboard data.

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