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

Annotations already establish a safe, idempotent, read-only local operation, so the bar is lower. The description still adds real behavioral context beyond them: counts-only scope, the upsell boundary to the counterparty pack, and the counting rule that a routing-hop-only address is not a payee.

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?

Dense but front-loaded: the primary use case and its returned fields come first, then the upsell boundary and the no-address fallback. Every clause carries information, though the list of counted fields is packed into one long sentence.

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 carries the burden of explaining return values and does so by enumerating the counts, time bounds, and exclusions. Domain terms (L7, Bazaar, binding confidence) are left undefined, but the shape of the response is clear enough to call and interpret the 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 coverage is 100% and the single optional parameter already documents both accepted forms (0x address, x402 URL) plus the omit-for-top-endpoints behavior. The description largely restates that dual mode, adding no format or validation detail the schema lacks, 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 resource (payments received by one Base address or x402 URL) and the exact quantities returned (counted payments, distinct agents, L7+ agents, first/last seen, excluded hops). It also distinguishes itself from the paid 'counterparty pack' that carries the payer list, so an agent can tell the two apart without opening schemas.

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?

Clear context for use: it is a free counts-only preview, and the full payer detail lives in the counterparty pack. It also defines the no-address fallback (top endpoints paid by the most ranked agents). It stops short of explicitly naming a sibling tool to switch to, but the selection condition is unambiguous.

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