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

Beyond the readOnly/idempotent/non-destructive annotations, it discloses that data is cryptographically signed with a published Ed25519 key, that tester wallet and transaction are redacted as hashes until the wallet is retired, that the operation is free, and that coverage starts on a fixed date. Those are exactly the traits an agent cannot infer from structured fields and would otherwise be surprised by.

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?

Purpose is front-loaded in the first clause, followed by usage routing, then behavioral caveats, then availability/cost — a sensible order with no filler sentences. It is dense, packing output fields, signing, redaction, and date bounds into roughly three sentences, which is close to the limit but each clause carries unique information.

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?

An output schema exists, so return values need not be specified, yet the description still signals what evidence is present and in what form (hashes plus signature). Combined with the redaction rule, date boundary, and cost note, an agent has everything needed to call this correctly and interpret the result.

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 explains both 'url' (full URL including path) and 'limit' (1-50, newest first, default 10). The description only reinforces that the target is a single x402 endpoint; it adds no format, normalization, or ordering semantics beyond the schema, 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 and resource — 'Get the signed receipts for our real test payments to one x402 endpoint' — and enumerates the payload (payment terms and response as SHA-256 hashes, amount quoted/paid, payout wallet, HTTP status, result, time, Ed25519 signature). It explicitly contrasts with the sibling check_endpoint, so an agent can separate this evidence-retrieval tool from the grading tool without opening either 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 an explicit when-to-use condition ('when a user or agent wants evidence behind a grade instead of the grade alone') and names the alternative that supplies the grade ('check_endpoint gives the grade itself'). It also adds a temporal eligibility constraint ('receipts exist for tests since Nov 7, 2026'), which prevents calls that would silently return nothing.

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