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

Annotations already declare readOnly/idempotent/non-destructive, yet the description adds substantive behavior: the three possible verdicts (passed, blocked, unavailable), that invoice_pay auto-runs this and refuses with receiver_blocked, and that paid checks (Scorechain/Merkle Science) return paid_check_requires_invoice (400) here. These are non-obvious failure modes and costs that annotations cannot convey.

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?

Front-loads the core action in the opening clause, then layers scope, then integrations. It is dense but not padded; the only mild redundancy is the paid-check caveat appearing both in the description prose and again in the schema's `checks` description.

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 return-value burden and does so ('Returns verdict passed, blocked or unavailable, with each check'). It also covers cost, error codes, and the invoice-flow integration — everything an agent needs to call it 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 coverage is 100%, so the baseline is 3. The description goes further by explaining the trap around the `checks` parameter: it is 'kept for compatibility; leave it out', costs 0.15/0.60 USDC, and is refused here with a specific error code — meaning an agent understands not just the type but why it exists and what will happen.

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?

Opens with a specific verb + resource + scope: 'Check any wallet (EVM 0x address or Solana base58, case-sensitive) before paying it'. It then enumerates exactly what is checked (OFAC SDN, issuer freeze lists, fund trail), which distinguishes it from sibling tools like invoice_pay or swap_build without requiring 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?

Gives an explicit when ('before paying it or taking its money'), names the automatic alternative ('Paying an invoice (invoice_pay) runs this check... so a payment... never reaches a sanctioned or frozen wallet'), and names exclusions ('Plain swaps (swap_build, double_build, nn_build) do not run it'). An agent can route correctly with no inference.

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