Get invoice

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

Declares read-only nature, which is the key behavioral trait. No annotations provided, so description carries the burden. Lacks mention of permissions or rate limits, but acceptable for a simple get.

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?

Single, well-structured sentence that conveys purpose, method, and options without waste. Front-loaded with core action.

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 no output schema and simple parameter set (2 params, no enums), description covers retrieval by key and optional expansion. Could hint at return structure, but missing is minor.

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?

Adds meaning beyond schema: clarifies 'expand' options (LineItems, Payments, Data) and that invoiceKey is the Karbon InvoiceKey. Schema coverage is 100%, so baseline is 3; description adds value.

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 verb 'Get' and resource 'a single invoice by InvoiceKey', with explicit read-only note and optional expansion. Differentiates from sibling 'list_invoices' by specificity.

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?

Indicates use when you have an InvoiceKey and optionally need related data. Implicitly contrasts with list_invoices for multiple records, but lacks explicit when-not or alternative references.

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