fusion-cad-ai

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execute

Run Python code in a Fusion sandbox to build, measure, and inspect CAD geometry in millimeters, then export STEP, STL, 3MF, or F3D files.

Instructions

Python в песочнице Fusion. Хелперы: make_box_mm, mm, show, measure.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "code": "<code>"
    },
    "name": "execute"
  }
}

Input Schema

Name	Required	Description	Default
`code`	Yes
`timeout_s`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.0.0Sep 29, 2026

TDQS

C2.4/5.0

Behavior2/5

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

Annotations say readOnlyHint=false, idempotentHint=false, destructiveHint=false, so this may mutate its sandbox but is not destructive. The description adds nothing beyond that: no statement about execution sandbox limits, the 120s default timeout, side effects on the Fusion document, or what a run returns. For an arbitrary-code-execution tool with only partial annotation coverage, that is a real gap.

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

Conciseness4/5

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

Two very short sentences, front-loaded with the essential fact (Python sandbox) and then the available helpers. No padding, though the brevity is partly under-specification rather than discipline.

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

Completeness2/5

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

For an arbitrary code execution tool with no output schema, no annotation detail on persistence or auth, and 0% parameter documentation, the description is too thin. An agent cannot tell scope of effects, timeout behavior, or how helpers are exposed.

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

Parameters2/5

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

Schema description coverage is 0%, so the description must carry the burden for 'code' and 'timeout_s', yet it explains neither. The helper names (make_box_mm, mm, show, measure) hint at the code environment but do not document the parameters.

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

Purpose3/5

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

States that it runs Python in a Fusion sandbox, which is a concrete verb+resource, but it never distinguishes itself from the sibling tools 'script' and 'execute_file', which plausibly do overlapping things. The helper list adds flavor but not differentiation.

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

Usage Guidelines2/5

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

There is no guidance on when to use this versus 'script' or 'execute_file', no prerequisites, and no conditions or exclusions. The agent must infer usage purely from the name.

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