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

The annotations already indicate readOnly=false and destructive=false, and the description confirms this is a mutating 'Add' operation. However, the description does not disclose additional behavioral traits such as optimistic-concurrency behavior, validation rules, or whether a parent document must already exist.

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, clear sentence with no filler. It includes useful examples of document types in parentheses, making it concise and scannable.

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?

The description is minimal and relies heavily on the input schema for context. It does not mention key operational constraints—such as the need for a parent quinvoice, how line totals are derived, or interaction with tax/cost fields—so despite the rich schema, the high-level description leaves some contextual gaps.

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?

The input schema has 100% coverage with detailed per-parameter descriptions, so the baseline is 3. The main description does not add extra meaning to the parameters; it only labels the operation generically, while the schema carries the semantic weight.

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's function: adding a line item to a document, with explicit document types (invoice, quote, bill). The verb 'Add' and the resource 'line item' are specific enough to distinguish this from update or delete operations.

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 implies usage—it says 'Add' and targets line items—but it does not explicitly contrast with sibling tools like update_document_item or delete_document_line. The parameter description for 'id' mentions 'Required on update_document_item; omit on add_document_line,' which provides indirect guidance but not a full when-to-use statement.

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