Invoice a customer's balance (write)

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

With no annotations provided, the description carries the full behavioral burden and does so thoroughly: it discloses that the invoice is issued for real, that an immediate charge is attempted for customers on automated payment, and that the invoiced amount depends entirely on existing balance lines. This goes well beyond a generic 'creates an invoice' statement.

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: the WRITE marker and core action appear first, followed by the balance-source dependency, the real-world charge behavior, and the recommended follow-up tool. Every sentence contributes useful guidance with no filler.

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?

Given there is no output schema and no annotations, the description supplies the essential context an agent needs: what is invoiced, what happens if the balance is empty, the real payment side effect, and how to retrieve the resulting invoice/PDF. It is sufficiently complete for correct invocation.

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 already documents all six parameters with 100% coverage, so the baseline is 3. The description does not add parameter-specific detail beyond what the schema provides, though it does clarify the overall relationship between balance lines and the invoice amount.

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 states a specific action ('Creates an invoice from the lines currently sitting in a ProAbono customer's balance') and clearly distinguishes the tool from siblings by naming create_balance_line and get_invoice. The WRITE prefix and title reinforce the operation's nature without ambiguity.

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 tells the agent when to use the tool in sequence: create_balance_line runs first to determine the amount, bill_customer invoices that balance, and get_invoice should be used afterwards. It also warns that billing an empty balance invoices nothing, giving a practical when-not-to condition.

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