Update invoice

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

The description goes well beyond the annotations: it discloses that the line array is replaced wholesale, omitted lines are dropped, and totals will change. It also warns that the operation is not idempotent, that it overwrites the live record, and that existing linked payments are not adjusted. This is richly transparent for a destructive write operation.

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 compact and front-loaded: purpose first, then usage, then behavioral caveats. Every sentence earns its place, and the most important warning about wholesale line replacement appears early. Despite covering several distinct risks, it avoids bloat.

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?

For a destructive mutation with annotations already marking it non-idempotent and destructive, the description supplies the missing operational details: the stale-token failure mode, the need for a fresh SyncToken, the replacement semantics, and the interaction with linked payments. With an output schema present, nothing critical is left for the agent to infer.

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 100%, so the baseline is 3. The description reinforces the key semantic point that the lines array is a full replacement, and it restates the SyncToken freshness requirement, but most of this is already present in the parameter descriptions. It does not add substantially new per-parameter meaning beyond what the schema provides.

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 a specific verb and resource: "Replace the contents of an existing invoice." It then names concrete use cases (correct amounts, dates, or the billing customer), making it immediately distinguishable from sibling update_customer and update_payment tools. The wholesale-replacement warning further pins down what this tool uniquely does.

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?

It explicitly states when to use the tool: to correct amounts, dates, or the billing customer on an existing invoice. It also gives crucial procedural context, requiring the Id and a fresh SyncToken from get_invoice, and warns that stale tokens fail with error 5010. It does not explicitly enumerate when not to use it or name an alternative for payment adjustments, but the guidance is otherwise clear.

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