Mark an invoice paid

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

With no annotations provided, the description carries the full burden of disclosure. It explicitly reveals additive behavior, overpayment refusal with open-balance feedback, and the full-payoff default when amount is omitted. It does not describe the response or whether the invoice status changes, but the critical behavioral surprises are disclosed.

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 two sentences with no filler. It front-loads the core action, then packs the most important behavioral details and the optional-amount shortcut into minimal space. Every sentence contributes directly to correct tool usage.

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 moderate-complexity mutation tool with no output schema, the description covers the essential call semantics: what happens on partial payment, overpayment, and full payoff. Minor gaps remain around the return value and how the invoice's paid status is reflected, but an agent has enough to invoke the tool correctly.

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 high at 80%, so the baseline is 3. The description adds meaningful emphasis to the 'amount' parameter semantics (additive, never replacing, omit to pay in full), but it does not add extra explanation for the required 'number' parameter or the optional metadata fields, which remain under-specified.

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?

Description clearly states the action ('Record a payment') and the resource (an invoice), and the title reinforces the intent. It is immediately distinguishable from sibling tools like invoice_get, invoice_list, and invoice_create because it focuses on recording payment against an existing invoice.

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 gives clear practical usage context: call this when receiving a payment for an invoice, and explains the key behavior of adding to existing paid amounts and handling full payoff by omitting amount. It does not explicitly name alternatives or exclusion criteria, but the context is strong enough for an agent to select it appropriately.

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