billy_create_invoice

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

Discloses default state (draft), write operation, and confirmation requirement. Without annotations, the description provides necessary behavioral context. However, it could mention that creation is non-destructive.

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?

Short and front-loaded: one sentence plus a compact shape definition. Every part is useful, no waste.

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?

Adequate for a creation tool, but missing return value information. No output schema exists, so the description should indicate what is returned (e.g., the created invoice object).

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 provides a detailed shape for the 'invoice' object (contactId, entryDate, currencyId, lines with fields), which is not present in the schema (only 'object' with additionalProperties). This compensates for low schema coverage and adds significant meaning.

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?

Clearly states 'Create a new invoice (default state: draft)' with a specific verb and resource. Distinguishes itself from sibling tools that involve invoices (approve, attach, delete, etc.).

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?

Mentions 'WRITE — requires confirm:true', instructing the agent to use confirm for execution. However, it does not explicitly state when to use this tool versus alternatives like billy_update_invoice.

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