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

With no annotations, the description carries the full behavioral burden for a mutation tool, yet it says nothing about permissions, whether the invoice is a draft or immediately final, numbering/auto-increment effects, e-Factura implications, or reversibility. 'Create' implies a write, but the significant consequences of that write are left entirely undisclosed.

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?

One tight sentence with zero waste and the action front-loaded. It is efficient, though its brevity borders on under-specification rather than exemplary conciseness.

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 14-parameter mutation tool with nested line items, no annotations, and no output schema, a single sentence is not enough — the agent gets no information about return value (ID? number?), side effects, or error handling. The rich schema covers inputs but the descriptive layer is nearly empty for a consequential write operation.

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 100%, so the schema already documents all 14 parameters in depth (currency, due_days, series fallback, per-line discount gating). The description adds no parameter meaning beyond naming 'line items', so the baseline 3 is appropriate given the schema does the heavy lifting.

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?

States a specific verb and resource ('Create a new invoice') plus scope ('for a client with one or more line items'), so the agent knows exactly what is produced. It does not distinguish this tool from close siblings like create_proforma_invoice, create_simplified_supplier_invoice, or create_supplier_invoice, leaving the agent to infer from names alone.

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 no guidance on when to use this instead of create_proforma_invoice, create_simplified_supplier_invoice, or create_order, nor any prerequisites (client setup, series availability). Apart from the schema hinting at series fallback via list_series, the description offers nothing on selection or sequencing.

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