create_invoice

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

Without annotations, the description discloses that the invoice is created as a draft, not finalized. It details the unit format (major units) and line structure. However, lacks information on idempotency, authorization, or error states.

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 well-structured, front-loading the key action, followed by a clear note on units, then a bullet-like list of line fields and arguments. Every sentence adds value without redundancy.

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?

Covers most parameters but omits notes, currency, and due_date (though optional). No output schema exists, so return value is not explained. For a 7-parameter tool with 3 required, the description is quite complete but could mention the optional fields.

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 coverage is 0%, but the description thoroughly explains parameters: contact_id, doc_date, series_id, lines format with field-level details (description, quantity, unit_price in euros, tax_type_id, discount_pct, irpf_rate). It compensates fully for the missing schema descriptions.

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 'Create a DRAFT sales invoice', with a specific verb and resource. It distinguishes from sibling tools like issue_invoice and get_invoice by emphasizing the draft nature.

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?

Explicitly instructs to call issue_invoice to assign a number, providing clear when-to-use guidance and indicating that this tool only creates drafts. Also specifies required arguments.

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