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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds context beyond those annotations by noting that parts are parametric, datasheet-dimensioned, and that insertion happens through a separate edit_project addPart operation, clarifying that this tool only supplies the catalog.

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?

Four short sentences, each earning its place: contents, parametric nature, insertion path, and a usage heuristic. The most important scoping information is 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?

For a simple read-only list with two optional params and full safety annotations, the description covers the catalog contents, part properties, and how to act on a result. It does not spell out the exact return shape, but the low complexity and schema coverage make the definition complete enough for correct invocation.

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 the parameters are already described. The description adds value by enumerating example categories (brackets, fasteners, spacers, board/motor reference bodies, mechanism pieces), which helps the agent choose useful search or category values even though it does not describe the parameters directly.

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 title and description make clear this tool browses OwlCAD's built-in parametric part library, naming concrete categories like brackets, fasteners, and reference bodies. It does not explicitly use a verb like 'list' in the description and does not name a sibling alternative, so it stops short of full 5-level differentiation.

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 gives an explicit when-to-use directive: reach for this before hand-modelling something that sounds standard. It also indicates the next step (insertion via edit_project addPart), but it does not name specific alternative tools or state when not to use this list.

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