Add payment to invoice

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

Annotations already include destructiveHint=true, but the description adds valuable context by stating 'DESTRUCTIVE: records money movement,' clarifying what the destructive action entails. It also notes currency constraints, going beyond the schema. No contradiction with annotations.

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-loaded with the core purpose. It delivers the key usage modes, a cross-reference, and a warning in just two sentences, with no filler or repetition of schema property names.

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 mutation tool with no output schema, the description effectively covers the primary use cases, currency requirement, and destructive nature. It does omit details like idempotency or response behavior, but given the annotations and rich schema, it is sufficiently complete for selection and invocation decisions.

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 baseline is 3. The description adds relational meaning by explaining the two payment modes: gateway_id for offline/manual and payment_details_id for stored methods. It also reinforces the amount currency requirement already in the schema. This extra guidance justifies a 4.

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 clearly states the tool records a payment against an invoice, with a specific verb ('Record a payment') and resource ('invoice'). It distinguishes two distinct modes (offline gateway or stored payment method), separating it from sibling tools like refund_invoice or apply_client_credit.

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 provides clear when-to-use guidance: 'typically an offline/manual payment through an offline gateway (see list_gateways), or charge a stored payment method.' It references the relevant gateway-listing tool, but does not explicitly state when not to use alternatives (e.g., apply_client_credit), so it falls short of a full 5.

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