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pzfreo

build123d-mcp

import_cad_file

Import STEP, STL, or 3MF files as named objects to visualize, measure, or compare against existing models. Supports multi-object 3MF with per-part registration.

Instructions

Import a STEP (.step/.stp), STL (.stl), or 3MF (.3mf) file as a named object in the session. path: absolute or relative path to the file. name: name to register the shape under (defaults to the filename stem). The shape becomes both the named object and the current_shape. A multi-object 3MF registers an aggregate under name plus each member as name_1, name_2, etc.; the result includes per-member topology summaries. After importing, use render_view() to visualise the shape, measure() for geometry queries, or compare(a='imported', b='model', kind='shape') to diff against a show() object. Note: STL imports produce a shell (volume=0) rather than a solid. 3MF commonly yields editable solids when its meshes are closed, but callers must check the returned solids and volume fields rather than assuming every mesh is valid. If you have both the original built shape and an imported copy in session.objects, render the imported one by name (e.g. objects='mypart') to avoid Z-fighting artifacts from two co-located shapes.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
nameNo
pathYes

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes
Behavior5/5

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

The description goes far beyond the annotations (readOnlyHint=false, destructiveHint=false) by detailing side effects: the shape becomes both the named object and current_shape, multi-object 3MF creates aggregate and member entries, STL imports yield a shell (volume=0), and 3MF solids require caller validation via returned fields. This provides essential behavioral context.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is detailed but every sentence serves a purpose: purpose, parameters, state change, multi-object behavior, format caveats, and usage tips. It is front-loaded with the main action and progressively adds necessary detail without waste.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description covers all critical aspects: formats, parameters, session state, output characteristics (per-member summaries, solids/volume fields), and post-import actions. It is comprehensive enough for an agent to use the tool correctly and anticipate common pitfalls.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

With 0% schema description coverage, the description fully explains both parameters: path (absolute/relative) and name (with default filename stem). This compensates entirely for the schema's lack of descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool imports CAD files (STEP, STL, 3MF) as named objects, with explicit format extensions. It distinguishes this from sibling tools by focusing on the import action and resulting session state, making it unambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides clear context for when to use this tool, including post-import workflow (render_view, measure, compare) and a specific Z-fighting avoidance scenario. It lacks explicit 'when not to use' or alternative import tools, but the guidance is strong enough for correct usage.

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

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