update_invoice

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

With no annotations, the description carries full burden for behavioral disclosure. It states 'Only provided fields will be updated', which hints at partial update behavior. However, it does not disclose idempotency, side effects, validation rules, error conditions, or required permissions. For a mutation tool, this is insufficient.

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 consists of two concise sentences with no filler. The first sentence states the action and scope, the second clarifies the update behavior. Every word 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?

Given the tool is a mutation with 12 parameters, no output schema, and no annotations, the description is too brief. It omits essential context such as return value (e.g., updated invoice object), error handling, prerequisite conditions, and the exact meaning of 'only provided fields' (e.g., if null vs omitted fields are treated differently).

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?

Input schema has 100% coverage with descriptions for all 12 parameters, so the schema already documents each parameter. The description adds no additional semantic detail beyond summarizing the schema fields. Baseline 3 is appropriate.

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 it updates an existing invoice and lists the categories of fields (subject, dates, terms, taxes). This distinguishes it from sibling tools like create_invoice (create vs update) and get_invoice (read). The verb 'update' and resource 'invoice' are specific.

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 implies usage for modifying existing invoices by stating 'Update an existing invoice'. However, it does not provide explicit guidance on when to use this tool versus alternatives (e.g., other update tools like update_client), nor does it mention when not to use it or prerequisites (e.g., invoice must exist, user must have permission).

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