update_invoice

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

With no annotations provided, the description must fully communicate behavioral traits. It only states 'Update an invoice by ID (GUID),' omitting critical details like idempotency, permission requirements, error handling (e.g., if invoice not found), side effects, or whether it returns the updated object. The presence of an output schema is not mentioned.

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 a single sentence of six words, highly concise with no wasted text. It front-loads the essential verb and object. However, the brevity may sacrifice necessary detail, but for a simple operation it is appropriately sized.

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?

Despite simplicity (2 required params, output schema exists), the description is too minimal. It does not explain the role of fields_json, the expected output, or how it relates to sibling invoice tools. The sibling list suggests many invoice operations, but the description fails to anchor the tool's specific function within that ecosystem.

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 input schema has 0% description coverage, so the description must add meaning. It clarifies that invoice_id is a GUID, which adds minimal value. However, it provides no explanation for fields_json, leaving its format and allowed values completely unspecified. Given the low coverage, the description should do more to explain both parameters.

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 the action (Update), the resource (invoice), and the identifier (by ID, GUID). It distinguishes from sibling tools like approve_invoice or generate_invoice by specifying the update operation. However, it does not elaborate on what parts of the invoice can be updated, which could be clearer.

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 provides no guidance on when to use this tool versus alternatives such as approve_invoice, generate_invoice, or other update tools in the sibling list. It lacks explicit context about when to choose update_invoice over creating or deleting an invoice.

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