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fusion-mcp

assembly_set_joint_limits

Set motion limits for a joint's degree of freedom to control rotation or slide ranges. Specify min/max values or disable limits per DOF in Fusion 360 assemblies.

Instructions

Set the motion limits of one degree of freedom: rotation/pitch/yaw/roll in degrees, slide/primary_slide/secondary_slide in mm. A number enables the limit, "off" disables it, omitted keeps it. dof must exist for the joint type (revolute: rotation; slider: slide; cylindrical/pin_slot: rotation, slide; planar: primary_slide, secondary_slide, rotation; ball: pitch, yaw, roll), and min must not exceed max, otherwise INVALID_PARAMS.

Returns {"joint": joint object (see assembly_create_joint) with "limits"}.

Example: assembly_set_joint_limits(joint="Jt=", dof="rotation", min=0, max=110) -> {"joint": {"limits": {"rotation": {"min": 0.0, "max": 110.0, "rest": null}}, ...}}.

Input Schema

NameRequiredDescriptionDefault
dofYesDegree of freedom of the joint's type
maxNoLimit in degrees (rotations) or mm (slides); "off" disables it
minNoLimit in degrees (rotations) or mm (slides); "off" disables it
restNoLimit in degrees (rotations) or mm (slides); "off" disables it
jointYesJoint or as-built joint ref (assembly_list_joints)

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.0

TDQS

A4.4/5.0
Behavior4/5

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

With no annotations, the description carries the full burden and does well: it discloses mutation semantics (omitted keeps the existing limit), validation failure mode (INVALID_PARAMS), and the return payload shape with a worked example. It omits permission/undo considerations, but the critical behavioral facts for correct invocation are present.

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?

Front-loaded with the action and units, then constraints, then return shape and example — dense and mostly waste-free. Some unit/'off' semantics duplicate the schema text, a minor redundancy in an otherwise efficient block.

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?

No output schema exists, yet the description supplies the return structure, an example response, the error code on invalid input, and full DOF validity rules. An agent has everything needed to call it correctly in one read.

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

Parameters4/5

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

Schema coverage is 100%, so baseline would be 3, but the description adds real meaning: the enable/disable/keep semantics of null vs number vs 'off', the per-joint-type valid DOF mapping, and the min<=max constraint. This goes beyond the terse schema 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?

States a specific verb and resource ('Set the motion limits of one degree of freedom') and immediately enumerates the DOF vocabulary in units, so the agent knows exactly what is being modified. It is clearly distinguishable from sibling joint tools (assembly_create_joint, assembly_drive_joint, assembly_list_joints).

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?

Gives concrete preconditions — dof must exist for the joint type (with a per-type mapping) and min must not exceed max — plus the value convention (number enables, 'off' disables, omitted keeps). It does not explicitly compare against alternatives such as assembly_create_joint, which may also accept limits, so no exclusion guidance.

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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