Create a new purchase invoice

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

Beyond the annotations, the description clarifies important behavioral semantics: amount is the gross amount and vat_amount is the VAT portion derived from it. It also identifies the exact endpoint path, adding context that the agent would otherwise have to infer.

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 short and front-loaded, but it unnecessarily repeats 'Create a new purchase invoice' verbatim in the first two sentences. The endpoint line and semantic clarifications are useful, but the duplication prevents a higher score.

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 create operation with a nested object schema and no output schema, the description conveys the key prerequisite and the amount/VAT semantics. However, it does not mention response behavior, validation failures, or the optional nature of fields like collect and pdf, so complete guidance for invocation is still somewhat lacking.

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 description adds meaning beyond the schema by explaining that each line's amount is the gross amount and that vat_amount is the VAT portion of that amount. This nuance is not fully explicit in the schema and helps the agent compute or validate invoice lines correctly, even though many parameters are already well described in the schema.

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 uses a specific verb and resource: 'Create a new purchase invoice' and the endpoint 'POST /invoices/purchase'. It clearly identifies the object being created, though it does not explicitly contrast with sibling tools like create_sales_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 an explicit prerequisite: call /invoices/purchase/options first to determine valid vat_id and ledger_id combinations. This provides actionable usage context, but it does not state when this tool should be preferred over alternatives or list exclusions.

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