proforma_invoices_update

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It discloses the crucial 'replaces all line items' destructive behavior and the draft-status requirement, which are the two most important behavioral traits. However, it doesn't mention whether updates to non-draft invoices fail or are ignored, what happens to required fields if omitted, or any permission/authorization requirements.

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 three concise sentences with front-loaded purpose. Each sentence earns its place: the verb+resource, the draft status constraint, and the line replacement behavior. It's appropriately brief for a tool with a well-documented schema and doesn't repeat information already present in the parameter descriptions.

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 complex mutation tool with 23 parameters (8 required), the description covers the critical behavioral facets: the draft-status gate and the destructive line-item replacement. No output schema exists, so return-value details aren't expected. The description doesn't cover edge cases like partial updates (can notes be updated alone?) or whether all required fields must be re-sent, but given the schema's thoroughness, this is a reasonable trade-off.

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 schema already documents all 23 parameters thoroughly. The description adds meaningful value beyond the schema by explaining the 'lines' array replaces all existing line items, which is a semantic nuance not captured in the parameter description. It clarifies that the array semantic is full replacement rather than merge, which is high-value information.

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 states a specific verb+resource ('Update an existing proforma invoice') and adds the key behavioral constraint that only drafts can be updated. However, it doesn't explicitly distinguish from sibling tools like proforma_invoices_create, though the name itself makes the update-vs-create distinction clear. The draft-status restriction is valuable differentiator.

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 clear context that this is for updating existing invoices in draft status, which gives a usage boundary. It doesn't explicitly name alternatives (e.g., that proforma_invoices_create is for new invoices), but the draft-status precondition and the line replacement behavior together give practical usage guidance. It lacks explicit when-not-to-use exclusions or mention of related flows like convert or send.

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