open_part

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

With no annotations, the description carries the burden and does substantial work: it discloses the side effect (becomes the current part), import behavior (no history, but face tools still work), return info (solid body count and mass properties), and an error condition (assembly refused). Missing only finer details like path resolution or overwrite 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?

Front-loads the core action and keeps the follow-on behavior terse. The parenthetical enumeration of face operations is slightly awkward but each clause adds real behavioral information.

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 no-annotation, no-output-schema, single-parameter tool, the description is fairly complete, covering purpose, side effects, import semantics, return info, and an error condition. Minor gaps remain around path format and permission/error handling.

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?

Only one parameter (path) with 0% schema coverage, so the description must compensate. It partially does by naming accepted file types (.sldprt, STEP, IGES, Parasolid), effectively defining the value domain, but gives no format details (absolute vs relative path, etc.).

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 ('Open') plus resource (.sldprt / STEP/IGES/Parasolid import) and clarifies it becomes the current part. It also distinguishes itself from the assembly-oriented sibling by stating 'A file holding an assembly is refused.'

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?

Gives clear context for use (opening or importing a part) and an exclusion (assembly files refused, implicitly routing to open_assembly). It also names follow-up tools (list_features, list_dimensions), though it doesn't explicitly name the alternative tool to use for assemblies.

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