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

With no annotations provided, the description carries the full behavioral disclosure burden. It discloses a critical destructive behavior—sending `lines` or `charges` REPLACES them entirely—and a hard refusal on issued invoices. This goes beyond generic 'edit' language and materially protects the agent from making a destructive mistake.

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?

Two sentences deliver the essential message with no filler: the purpose is front-loaded, and the most dangerous behavioral caveats (replacement semantics and refusal on issued invoices) are stated plainly. Every sentence earns its place.

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 tool has 8 parameters, 0% schema coverage, no annotations, and no output schema. While the description covers the core use case and the most critical behavioral caveats, it leaves the semantics of most parameters unexplained and doesn't mention return values or error detail. It is adequate for invoking the tool but leaves clear 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?

The schema has 0% description coverage, so the description must compensate. It adds meaningful semantics for two key parameters (`lines` and `charges` with replace behavior), but the other six parameters (`id`, `notes`, `terms`, `dueDate`, `currency`, `issueDate`) receive no explanatory context beyond their names. The compensation is only partial.

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 opens with 'Edit a draft invoice,' a specific verb and resource combination. It further distinguishes itself from sibling tools like invoices_create_draft and invoices_issue by explicitly stating that issued invoices cannot be edited, so an agent can immediately identify its scope.

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 clear usage context: edit draft invoices only. It explicitly states a when-not condition ('Issued invoices cannot be edited and this will refuse'), though it doesn't name alternative tools for handling issued invoices, which would have made the guidance fully explicit.

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