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

Goes well beyond the readOnlyHint/openWorldHint annotations: discloses the free-tier rate limit (100/day), the exact data sources per chain (Base index of public USDC transfers into CDP Bazaar payTos vs. latest 200 ledger entries on XRPL/Stellar), a privacy guarantee (address not stored), and an honesty caveat ('Observations, not a guarantee'). This is the kind of context an agent needs to interpret results 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?

Cost and rate limit are front-loaded, followed by the core action, with caveats trailing. The single sentence is dense with nested parentheses and could be split for readability, but nearly every clause carries information an agent would otherwise have to guess.

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 one-parameter, no-output-schema read tool, the description covers the inputs, the shape of the return (per-seller summary line plus flags such as dead listing, delisted, failed checks, duplicate payments), the coverage window, and the limits of the data. Nothing material 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 coverage is 100% and the single parameter is already documented with accepted formats, so the description largely repeats it. It does add real meaning, though: the note that XRPL and Stellar reads cover only the latest 200 ledger entries tells the agent how the same address parameter behaves differently per chain.

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 with scope: 'list the x402 sellers that wallet paid in the last 90 days'. It also anchors itself to a sibling ('same plain summary line as lumi_trust_check'), so an agent can distinguish it from the single-seller check 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?

Clear invocation context: pass a public wallet address to get a payment-history view, with an explicit scope exclusion ('No price comparisons') and a cost/limit note. It stops short of naming when to prefer a sibling tool (e.g. lumi_trust_check for a single seller) or what to do when the 90-day/200-entry window is insufficient.

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