Record a manual payment method for a customer (write)

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

With no annotations, the description carries the behavioral disclosure burden. It clearly marks the operation as WRITE, notes that it changes nothing else about payment settings, and discloses that the endpoint refuses gateway-driven methods. It does not discuss overwrite/idempotency or error behavior, which are minor gaps for a simple two-parameter write.

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 front-loaded with 'WRITE' and the primary action, then adds exclusions and routing guidance. It is slightly redundant with the title's '(write)' and the schema's existing Card/DirectDebit exclusion, but every sentence carries useful selection and invocation information.

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 two-parameter tool with fully described schema and no output schema, the description is strong enough to select and invoke correctly. It would benefit from stating whether calling it again replaces an existing manual payment method and what a successful response looks like, but these do not block correct usage.

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 schema already documents both parameters and their enum meanings. The description adds human-readable context ('bank transfer, cash, cheque or other') and reinforces the manual-only constraint, but does not materially expand on the schema's parameter descriptions.

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 opens with a clear verb and resource: 'Records the manual payment method a ProAbono customer settles their invoices with.' It also distinguishes itself from sibling tools like get_payment_settings by framing this as a write operation that changes only the manual payment method, not other payment settings.

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?

It explicitly states when this tool applies: manual methods only (bank transfer, cash, cheque, other). It also gives a concrete exclusion and alternative: Card and DirectDebit are refused, and card setup should go through the Customer Portal, 'never through this tool.' This removes ambiguity about when to choose it.

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