Get invoice payment status

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

Annotations already declare readOnlyHint=true, so the agent knows this is a read operation. The description reinforces this by stating 'Read-only — this reports on collections, it does not record one.' However, it adds little beyond the annotation, merely elaborating the read-only nature. With annotations covering safety, a score of 3 is appropriate.

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 three sentences, front-loaded with purpose and return values, then usage guidelines. No wasted 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?

Despite no output schema, the description lists all returned fields (invoiceTotalAmount, paidAmount, unpaidAmount, paid flag) and gives example queries. It covers parameter count and usage context adequately.

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?

Input schema coverage is 100% with descriptions for all three parameters (number, seriesName, companyVatCode). The description does not add additional meaning beyond what the schema already provides, so baseline 3 applies.

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 tool answers whether an invoice is paid and returns specific amounts (invoiceTotalAmount, paidAmount, unpaidAmount) and a paid flag. It uses specific verbs ('answer', 'returns') and clearly distinguishes itself from sibling tools like create_payment.

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 explicitly provides example questions ('has invoice FF 120 been paid?', 'how much does this client still owe?') and advises to use it after create_payment to confirm effects. It also directs users to create_payment for recording payments, giving clear when-to-use and when-not-to-use guidance.

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