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

With no annotations, the description carries the full burden and does substantial work: it discloses API-key auth, a 1 CRD per-call charge that applies even to rejected calls, the 429 exemption, and that errors return a request_id for support escalation. Missing are rate-limit specifics beyond the 429 note and whether the charge applies to repeated retries within a session.

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?

Two dense sentences, front-loaded with purpose then billing/auth/error behavior, with parentheticals used efficiently for the 429 exemption. No sentence is filler.

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 5-parameter read tool with no output schema and no annotations, the description covers auth, cost model, error path, ordering, and returned fields, which is close to sufficient. It stops short of describing pagination past the limit cap or the meaning of credits_granted values.

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%, including the non-obvious x402_payment payload, so the schema handles parameter meaning. The description's field list (kind, status, payer, amount_usd, transaction_hash, credits_granted, error) reads as return fields rather than parameter semantics, adding little beyond what the schema already documents.

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 ('List this project's x402 stablecoin payments') plus an ordering ('newest first') and the returned fields, which differentiates it from generic siblings like get_transactions or list_deposits. It never names a sibling alternative explicitly, so the boundary is inferred rather than stated.

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?

Usage context is implied by the resource scope (x402 payment receipts for this project), and the cost/auth notes give surrounding context, but there is no explicit 'use this instead of X' guidance or a stated when-not condition. An agent must infer that this is the receipt-history counterpart to get_transactions.

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