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

Annotations already disclose that the tool is destructive, non-idempotent, and open-world. The description adds no behavioral context beyond restating that it adds items: it does not explain whether items are appended, whether duplicate calls create duplicates, how invoice totals are affected, or what permissions are required.

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, front-loaded sentence with no wasted words. It is efficiently structured, though its brevity contributes to information gaps that are better assessed under other dimensions.

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, non-idempotent mutation accepting a nested array of priced items with a 50% schema coverage and no output schema, the description is far too thin. It omits item requirements, quantity limits, append behavior, and any caveats an agent needs to invoke it correctly.

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 only 50%, so the description should compensate by explaining parameter semantics. Instead, it only says “priced line items” and does not mention the required item fields (name and unit_cost), the 100-item maximum, or the meaning of invoice_id. The schema carries most of the load, but coverage gaps remain unaddressed.

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 and resource: adding priced line items to an invoice. This is clear and distinguishes it from broader invoice tools like create_invoice or update_invoice, though it does not explicitly differentiate it from sibling tools such as add_change_order_items or add_estimate_items.

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?

There is no guidance on when to use this tool versus alternatives, no prerequisites such as the invoice needing to exist, and no mention of related tools like create_invoice or list_cost_codes. The usage context is only weakly implied by the tool name and description.

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