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

Annotations already declare non-readOnly, openWorld, idempotent, and non-destructive, but the description adds substantial context: it writes files plus a starter script to output_dir (default temp dir), evaluates it, refuses non-watertight STL unless allow_open, and enforces a 50 MB limit. What is missing is any note on auth/network failure behavior for url downloads.

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?

Dense but front-loaded, opening with the trigger condition and then the source constraint. It is long, yet nearly every clause carries operational weight; a couple of the return-shape details are arguably redundant given the output schema.

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?

Covers input constraints, side effects (file and script written), STL-specific caveats, the downstream handoff of script_path, and the return shape. For a complex import tool with nested upload objects, this is complete enough to call correctly without further guidance.

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 baseline is 3, but the description adds real value: 'give exactly one source' clarifies the mutual exclusivity of url/upload/content_base64 that the schema does not enforce, and it documents the 50 MB cap and format auto-detection vs override.

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?

States a specific verb and resource (import a STEP/STL file the user designed elsewhere or a vendor model) and produces named artifacts. It clearly differs from siblings like find_part/fetch_part, which retrieve catalog parts, and mesh_to_features, which it references for editable meshes.

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?

Explicitly says when to use it (user's own STEP/STL file) and gives the alternative condition for STL meshes (use mesh_to_features for an editable feature tree). Also names the three mutually exclusive source inputs and the size cap, leaving little to inference.

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