generate_due_invoice

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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the mutation nature is partly covered. The description adds nothing beyond that: it omits the 'confirm must be true' guard, does not clarify idempotency (whether repeated calls generate duplicate invoices), and gives no billing side-effect context, which matters for an invoice-generating mutation.

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?

A single front-loaded sentence with no filler, which is efficient. It is arguably under-specified rather than padded, but as pure structure it is tight and wastes no words.

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 billing mutation tool with no output schema, the description should convey what the call produces and its consequences. It does not explain the resulting invoice, billing period, or side effects, leaving the agent without enough context to invoke it confidently.

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%, with both 'id' (Server ID) and 'confirm' documented in the schema, so the baseline of 3 applies. The description adds no extra meaning about the parameters beyond what the schema already states.

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 gives a verb+resource ('Create the next invoice for a server'), which is better than a tautology, but 'next invoice' is ambiguous about billing period and cycle, and it is not distinguished from the closely related sibling create_addfunds_invoice. The parenthetical '(whmcs/generate_due_invoice)' is just an internal identifier and adds no disambiguating value.

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?

There is no guidance on when to use this tool versus alternatives such as create_addfunds_invoice, get_invoices, or mass_pay, nor any when-not or prerequisite conditions. The agent is left to infer the intended scenario entirely.

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