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

Annotations already declare mutation, non-idempotency, open-world behavior, and destructiveHint=true. The description usefully adds that the result is a draft and that line items are priced, but it does not disclose authorization needs, side effects, or why the destructive hint applies.

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?

A single efficient sentence with no filler. The core meaning is front-loaded and appropriately sized for this tool.

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?

The definition covers the core action and schema supports the parameters, but it lacks usage routing, prerequisites, and mutation side-effect context. For a seven-parameter create operation with destructive/open-world annotations, that leaves noticeable gaps.

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 71%, so many parameters are already documented in the schema. The description adds only high-level context about project/customer billing and priced line items, without clarifying precedence between project_id and customer_id or dependency details already handled by 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 gives a specific verb and resource ("Creates a draft invoice") plus scope ("for a project or customer, with priced line items"). It is clearly about invoice creation, though it does not explicitly distinguish itself from siblings such as add_invoice_items or send_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?

There is no explicit guidance on when to use this tool versus alternatives, nor any prerequisites or exclusions. The phrase "for a project or customer" hints at the project_id/customer_id choice, but the agent must infer all workflow conditions.

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