add_invoice_line

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

No annotations provided; description bears full burden. It only states 'add a line item' without disclosing side effects (e.g., recalculates totals, requires edit permissions, or whether the action is reversible). For a mutation tool, this is insufficient.

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?

Single sentence, front-loaded with primary action. Efficient but could be slightly more detailed without harming conciseness. No unnecessary words.

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 no output schema and 7 parameters (5 required), the description fails to explain return value (e.g., created line item ID) or constraints (e.g., only for draft invoices). Incomplete for an agent to reliably use without additional knowledge.

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% with descriptive parameter descriptions. The tool description adds no extra meaning beyond the schema, so baseline 3 is appropriate. No contradictions or omissions noted.

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?

Description explicitly states 'Add a line item to an existing draft invoice,' which is a specific verb and resource. It clearly distinguishes from sibling tools like 'create_invoice_with_lines' (which creates invoice and lines together) and 'update_invoice' (which modifies invoice header).

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?

No guidance on when to use this tool vs alternatives (e.g., 'create_invoice_with_lines' for new invoices, 'update_invoice' for header changes). No mention that the invoice must be in draft status, nor any prerequisites or exclusions.

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