RoslynMCP

MCP server that connects AI assistants to Visual Studio's Roslyn compiler for 100% accurate C# code analysis.

Platform: Windows only | Language: C# only

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Requirements

• Windows 10/11
• Visual Studio 2022 (17.9 or later)
• C# solution (.sln)

Supported AI Assistants

• Claude Code (Anthropic)
• GitHub Copilot (with MCP support)
• Cursor
• Any MCP-compatible client

Why RoslynMCP?

AI assistants typically use text-based search (grep) which produces false positives and misses semantic relationships. RoslynMCP uses the same Roslyn compiler that powers Visual Studio's IntelliSense.

When to Use

Use RoslynMCP for:

• Find all usages of a symbol (class, method, property)
• Refactoring - find all places that need to change
• Code understanding - type hierarchy, call graphs
• Analyze method overloads
• Find interface implementations
• Impact analysis - what breaks if I change this?

Use Grep/Glob for:

• Quick text search - strings, comments, TODO
• Non-C# files - XML, JSON, config
• Regex patterns
• Multi-file-type search

Installation

1. Install RoslynMCP from Visual Studio Marketplace
2. Open your C# solution in Visual Studio
3. Go to View → Other Windows → RoslynMCP
4. Copy the configuration for your AI assistant

Features

v1.11.0

• New: get_completions - Get code completion suggestions at any position (like IntelliSense)
• New: get_signature_help - Get method signature and parameter info during calls
• New: apply_rename - Rename symbols across entire solution with Roslyn accuracy

v1.10.0

• Fixed: reload_file now works correctly (was failing with "TryApplyChanges cannot be called from a background thread")

RoslynMCP provides 49 Roslyn-powered tools including:

• Navigation: Find references, definitions, implementations, callers/callees
• Analysis: Type info, class hierarchy, code metrics, data flow
• Diagnostics: Real-time errors, warnings, async issues, performance problems
• Refactoring: Rename preview, apply rename, impact analysis, extract method feasibility
• Code Intelligence: Completions, signature help

Troubleshooting

Extension not loading

• Check Visual Studio Output window for errors
• Verify extension is enabled in Extensions → Manage Extensions

AI assistant not connecting

• Ensure Visual Studio has a solution open
• Open the RoslynMCP tool window (View → Other Windows → RoslynMCP)
• Verify the server status shows "Running"

No tools available

• Make sure you copied the correct configuration for your AI assistant
• Restart your AI assistant after configuration changes

License

MIT