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

Annotations provide only generic hints (not read-only, not idempotent, not destructive), so the description carries most of the behavioral burden. It adds useful constraints: refusal on invoiced orders or backdated lines, and clarifies MINOR units. However, it does not describe what happens on success, side effects like order totals, or error behavior.

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, front-loaded with the core behavior and a clear constraint. Every clause contributes, and the parts/labour distinction is efficiently packed. Slightly dense but well structured.

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 10-parameter mutation tool with no output schema and unhelpful annotations, the description covers the core behavior and important refusal rules. Yet it omits expected return values, whether the line appends to existing lines, and the nature of errors on refusal. Acceptable but not complete.

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 90%, so the schema already documents each parameter with descriptions. The description repeats the parts/labour grouping and MINOR-unit semantics that are already present in the schema. It adds little new meaning beyond a concise summary; baseline 3 is appropriate.

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 a specific verb and resource: add a line (parts or labour) to a work order. It distinguishes parts vs labour branches and is clearly distinct from siblings like work_order_create or work_order_get. The purpose is unambiguous and identifiable even without opening the schema.

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 when to use the tool (adding a line to an existing work order) but does not explicitly route to alternatives. It states refusal conditions (invoiced order, date before request) but offers no guidance such as 'use work_order_create instead' or 'do not use for new orders'.

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