update_invoice

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

No annotations are provided, so the description carries the full burden. It discloses the draft-only editing restriction, which is a useful behavioral constraint. However, it does not describe error handling, permissions, or other side effects, which is a gap for a mutation tool.

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 that states the action and the key constraint without any filler or redundancy. It is well-structured and instantly parseable.

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 simple update operation, 100% schema parameter coverage, and no output schema, the description provides the essential constraint (drafts only). A touch more context about consequences of updating non-drafts or what happens after the update might be helpful, but the current description is adequate for this complexity level.

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%, with each parameter having its own description (id, notes, due_date, invoice_date). The tool description adds no additional parameter semantics beyond what the schema already provides, so a baseline score of 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 the action 'Update an existing invoice' with a specific verb and resource. It also adds the draft-only scope, which distinguishes it from other invoice-related tools like update_invoice_status.

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 parenthetical 'only drafts can be edited' gives clear context on when this tool is applicable and when it is not. However, it does not explicitly name alternatives for non-draft invoices or status changes, so it falls just short of a 5.

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