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

With no annotations provided, the description takes on full disclosure duty and does well by explaining the 'not_observable' rail limitation, instructing the agent never to assume unpaid, and stating that a settled invoice returns a receipt. It lacks explicit mention of whether the operation is read-only or whether errors or rate limits exist, but the provided caveats are substantial and behaviorally relevant.

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?

The description is compact and front-loads the core purpose and outcome enumerations in a single sentence. The parenthetical asides are dense but all earn their place by clarifying edge cases and the return behavior. Minor structural awkwardness (long clauses, nested dashes) keeps it from being perfectly elegant.

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?

The description explains the main statuses and the settled-return behavior, but without an output schema it does not fully describe the return structure for non-settled statuses. It also omits any guidance on how required parameters like 'to' and 'totalMicro' relate to invoice rebuilding, leaving a noticeable gap given the 7-parameter complexity.

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?

The schema description coverage is only 43%, yet the main description adds no parameter-level meaning. It mentions 'field-for-field' but never names or explains the individual parameters like to, number, dueDateMs, or merchantName, which are left undescribed in the schema. The description therefore fails to compensate for the low coverage.

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?

The description uses a specific verb ('Check') and resource ('an invoice'), then immediately enumerates the distinct outcomes: settled, overdue, issued, and not_observable. This clearly distinguishes it from sibling tools like till_check_payment and till_receipt by focusing on invoice status verification against the chain.

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?

The description clearly conveys when to use this tool: to check an invoice against the chain and obtain its status, with the additional guidance that a not_observable result should lead to checking the merchant's books rather than assuming non-payment. It does not explicitly name alternatives or exclusion criteria, so it stops short of a 5.

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