get_invoice_payment

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, establishing the safety profile. The description adds no further behavioral context, such as return value formats, authentication needs, or edge cases. It merely restates the basic action without going beyond 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 extremely concise ('Fetch a payment'), which is efficient but under-specified. It avoids verbosity but barely adds value beyond the tool name. While not as severe as 'Process', it lacks the substance expected for a resource-specific tool.

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 tool appears to fetch a payment associated with an invoice, but the description does not explicitly state this relationship. Given the absence of an output schema and the presence of a similar get_payment tool, the description should provide more context about what constitutes an invoice payment and what the response contains.

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 input schema fully describes both parameters (invoice_id and payment_id) with types and descriptions, achieving 100% coverage. The description adds no additional parameter semantics, so the baseline of 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?

The description 'Fetch a payment' clearly indicates a read operation on a payment resource. However, it does not distinguish this from the sibling tool get_payment, which also fetches a payment. The tool name suggests invoice-specific payments, but the description lacks that qualifier.

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 no guidance on when to use this tool versus alternatives like get_payment or list_invoice_payments. It does not mention context, prerequisites, or the relationship between invoice_id and payment_id.

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