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tbrito88
by tbrito88

Offset Curve

offset_curve

Offset connected sketch curves by a set distance in Fusion 360, using a direction point to control side. Specify a curve index and distance in cm to create a parallel sketch loop.

Instructions

Offset connected sketch curves by a distance. Direction is determined by the direction_point. Unless a parameter says otherwise, lengths and coordinates are in cm (not mm) and angles in degrees.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
curve_indexYesIndex of a curve in the connected loop
direction_xNoX of direction point
direction_yNoY of direction point
sketch_nameNoSketch name (default: most recent)
offset_distanceYesOffset distance (cm)

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.0

TDQS

B3.2/5.0
Behavior3/5

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

Annotations already declare readOnlyHint=false, idempotentHint=false, and destructiveHint=false, so the agent knows this mutates state, is not idempotent, and is non-destructive. The description adds a genuinely useful unit convention (cm not mm, degrees), but says nothing about whether a new curve is created or the original is modified, or about error behavior.

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?

Three short sentences, front-loaded with the core action, and the unit caveat is a non-obvious detail that earns its place. No filler.

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

Completeness3/5

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

With no output schema, the description should say more about the result — whether a new curve is added and whether the original curve is affected. Units and direction are covered, which is above average, but the mutation outcome is unspecified for a non-idempotent write operation.

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

Parameters3/5

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

Schema coverage is 100%, so the baseline is 3. The description reinforces the unit convention for offset_distance and explains that direction comes from direction_x/direction_y, but adds no syntax or range detail beyond what the schema already documents.

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

Purpose4/5

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

States a specific verb and resource: 'Offset connected sketch curves by a distance.' The 'sketch curves' scoping implicitly differentiates it from the sibling offset_faces, though no sibling is named explicitly. An agent can identify the operation and its target geometry.

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?

The description explains how direction is determined but gives no guidance on when to choose this tool over alternatives such as offset_faces, nor any prerequisites (e.g., an active sketch must exist). Usage context is left entirely to inference.

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