onshape-mcp
onshape-mcp is an MCP server that exposes a set of MCP tools for programmatic interaction with Onshape (document discovery, sketch/feature/assembly creation and analysis, variable table management, FeatureScript evaluation, and exporting CAD to common formats).
Score Breakdown
⚙ Agent Friendliness
🔒 Security
Uses Onshape API access key/secret key (implies HMAC-based auth) and recommends environment variables/.env rather than hard-coding secrets. However, the provided content does not describe secret redaction/logging behavior, fine-grained scope controls, or rate-limit protection; dependency health/CVE status is not evidenced.
⚡ Reliability
Best When
You want an AI agent to drive Onshape modeling tasks (including parametric updates) using a structured toolset, and you can supply Onshape API credentials securely.
Avoid When
You need a documented, stable REST/SDK contract with explicit rate-limit guidance, or you require formal guarantees on idempotency/retry semantics for write operations.
Use Cases
- • Creating and updating Onshape CAD models programmatically via an MCP-capable agent
- • Parametric design workflows using Onshape variable tables
- • Automating assembly construction (instances, mates, alignment) and basic interference checks
- • Evaluating FeatureScript expressions and extracting bounding boxes
- • Exporting CAD to STL/STEP/GLTF/OBJ formats from agent workflows
Not For
- • Building models without any Onshape account/API access
- • Use as a general-purpose public API for end users (it is geared toward agent/MCP tool calling)
- • High-assurance production automation without reviewing error behavior and idempotency characteristics
Interface
Authentication
Authentication appears to be handled using Onshape API credentials (access key + secret key) set as environment variables. No OAuth/scope model is described in the provided content.
Pricing
No pricing information for the package itself is provided; it appears to be a self-hosted open-source MCP server.
Agent Metadata
Known Gotchas
- ⚠ Write operations may be non-idempotent (retries could duplicate entities/features unless the server tracks prior state).
- ⚠ Unit/angle conventions: sketch dimensions in inches are stated; instance transforms use inches/degrees—agents must be careful with units.
- ⚠ Some instance transform operations are described as failing on fixed instances; agents should handle such failures and possibly re-create or adjust instance constraints.
Alternatives
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Scores are editorial opinions as of 2026-03-30.