Set a customer's next billing date (write)

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It discloses that the operation is a WRITE, guarantees no side effects on other payment settings, and explains the skip-versus-compress behavior for forward moves. It does not mention permissions or reversibility, but covers the most critical behavioral traits for a simple setter.

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?

Three sentences, each earning its place: purpose+scope, use case, and prerequisite+behavior. The 'WRITE' prefix is a useful immediate signal, and the most critical information is front-loaded. No filler or redundancy.

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 simple two-parameter setter with full schema coverage and no output schema, the description is quite complete. It covers purpose, usage context, a key behavioral nuance, and a prerequisite. It omits edge cases like backward date moves or error conditions, but these are minor for this tool's simplicity.

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 both parameters (customer_ref and date_next_billing) are already documented with clear descriptions and an example. The description does not add extra semantic meaning to the parameters beyond what the schema provides, so a baseline of 3 is appropriate. The 'moving forward' hint is behavioral rather than parameter-specific.

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 verb ('sets'), the resource ('the date of the next billing of a ProAbono customer'), and explicitly scopes the action ('changes nothing else about their payment settings'). This distinguishes it from sibling set_* tools like set_invoice_note and set_payment_method by focusing on billing date only.

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 provides a concrete use case ('align a customer's billing on a date the merchant chose... common anniversary, or end of negotiated period') and an explicit prerequisite with an alternative tool: 'Read the current value with get_payment_settings first'. It also warns about a behavioral consequence ('moving the date forward skips a period rather than compressing it'), which guides correct usage.

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