SolidWorks MCP — Architecture Analysis

Updated: April 8, 2026
Scope: Gap analysis between the documented 5-layer architecture (../user-guide/architecture.md) and the actual implementation.

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Background

The documented architecture describes intelligent runtime routing between COM and VBA execution paths, complexity-based adapter selection, response caching, and multi-layer security enforcement. The original codebase delivered a solid infrastructure foundation — adapters, pooling, circuit breaker, and 106 tools — but was missing the runtime intelligence layer entirely. This document tracks what was missing and what has since been implemented.

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Component Status

Component	Original State	Current State	Notes
MCP Protocol / JSON-RPC	✅ Complete	✅ Complete	FastMCP handles transport
Tool registry	✅ Complete (90+)	✅ Complete (106)	Exceeds documented count
Direct COM adapter	✅ Complete	✅ Complete	~2200-line pywin32_adapter
Circuit breaker	✅ Complete	✅ Complete	CLOSED/OPEN/HALF_OPEN state machine
Connection pool	✅ Complete	✅ Complete	FIFO AsyncIO queue; not load-aware by design
Complexity analyzer	❌ Missing	✅ Implemented	25+ operation profiles; param-count + history scoring
Intelligent router	❌ Missing	✅ Implemented	45+ operations; automatic COM/VBA selection + cache lookup
Response cache	❌ Missing	✅ Implemented	TTL in-memory cache; 20+ read-only operations cached
VBA adapter	⚠️ Tools only	✅ Implemented	VbaGeneratorAdapter + VbaMacroExecutor; registered in factory
Security enforcement	❌ Stubs	⚠️ Partial	API key + rate-limit enforced in tool path; no OAuth2 yet
Multi-instance load balancing	❌ Missing	🔮 Planned	Out of current scope; pool remains FIFO

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What Was Missing

The original gaps were all in the runtime intelligence layer, not the tooling itself:

• No complexity analysis — create_extrusion(21 params) always went directly to COM with no automatic VBA fallback.
• No intelligent router — adapter was selected once at startup; per-request routing didn't exist.
• No response cache — a cache directory was created on disk but no hit/miss logic existed anywhere in the codebase.
• No VBA adapter — VBA generation existed as standalone tools; users had to manually call generate_vba_part_modeling and then execute the output themselves.
• Security stubs — require_auth() was a passthrough decorator, setup_authentication() was empty, and rate limiting was implemented but never connected to the request path.

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What Changed

Complexity Analyzer (adapters/complexity_analyzer.py)

Scores each operation using a weighted formula:

score = (param_ratio × 0.45) + (profile_complexity × 0.40) + (history_failure_rate × 0.15)

25+ operations have explicit complexity profiles. Operations with high parameter counts (>12), known-complex profiles (sweep, loft, spline), or poor COM history are flagged for VBA routing.

Intelligent Router (adapters/intelligent_router.py)

Wraps the base adapter and intercepts calls to 45+ operations. On each call: check response cache → score complexity → route to COM or VBA path. Falls back automatically on failure, and updates performance history after each call.

Response Cache (cache/response_cache.py)

In-memory TTL cache with LRU eviction and deterministic key generation from operation name + payload hash. 20+ read-heavy operations are cached (model info, mass properties, drawing analysis, feature listing, docs discovery). TTL and capacity are configurable via config.py.

VBA Adapter (adapters/vba_adapter.py, adapters/vba_macro_executor.py)

VbaGeneratorAdapter wraps the COM adapter and generates operation-specific VBA code with metadata annotations. VbaMacroExecutor handles the macro lifecycle: write to temp file → call RunMacro2 → track result + cleanup. Registered in the adapter factory under AdapterType.VBA.

Security (security/runtime.py, security/auth.py)

API key validation and per-client rate limiting are now enforced in the tool invocation path via a SecurityEnforcer inserted before each tool call. Full OAuth2/JWT transport-level auth is a future item.

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Remaining Gaps

Gap	Impact	Priority
Multi-instance load balancing	FIFO pool only; multiple SW processes not distributed intelligently	Low — single-machine is standard
OAuth2 / JWT	Remote deployments rely on API key or IP allowlisting	Medium — needed for hosted deployments
Security level → tool access control	security_level config field unused; all tools always accessible	Medium
Persistent performance history	Complexity analyzer resets on restart; no SQLite backing yet	Low — degrades gracefully

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Tool Registry

106 tools across 12 modules (exceeds documented 90+). All registered with FastMCP and backed by Pydantic input schemas.

analysis.py            5 tools
automation.py          8 tools
drawing.py            12 tools
drawing_analysis.py    8 tools
export.py              7 tools
file_management.py    14 tools
macro_recording.py     7 tools
modeling.py            9 tools
sketching.py          18 tools
template_management.py 6 tools
vba_generation.py     10 tools
docs_discovery.py      2 tools
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Total                106 tools