invoices_add_line_item

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

With no annotations, the description carries the burden of behavioral disclosure. It reveals that when product_id is used, it auto-fills name, cost, and price, which is beyond basic schema. However, it does not mention side effects like updating total, permission requirements, or response format.

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?

Two sentences with no wasted words. First sentence states the purpose, second provides a key usage tip. Efficient and front-loaded.

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 has 15 parameters and no output schema, the description is reasonably complete. It covers the primary use case and the auto-fill behavior. However, it lacks information about the return value or result of the operation, which would be helpful since no output schema is provided.

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 coverage is 100%, so parameters are already documented. The description adds value by explaining that product_id+quantity is sufficient and triggers auto-fill, providing workflow guidance beyond the schema.

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 tool adds a line item to an invoice, which is a specific verb+resource combination. It distinguishes itself from sibling tools like invoices_delete_line_item or estimates_add_line_item by being invoice-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 hints at a usage pattern (using product_id to auto-fill) but does not provide explicit guidance on when to use this tool versus other add_line_item tools for different entities (estimates, tickets, scheduling). No when-not-to-use or prerequisites are mentioned.

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