MCP Servers

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.

| Criteria | RoslynMCP | Grep/Glob | |----------|-----------|-----------| | Symbol search accuracy | ✅ 100% (semantic) | ⚠️ ~80% (text-based) | | Distinguishes overloads | ✅ Yes | ❌ No | | Understands types | ✅ Yes | ❌ No | | Call hierarchy | ✅ Callers/Callees | ❌ No | | Interface implementations | ✅ Yes | ⚠️ Regex hacks | | Method overrides | ✅ Yes | ⚠️ Regex hacks | | False positives | ✅ 0% | ⚠️ Possible (comments, strings) |

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

v1.13.2

• New: extract_interface - Extract interface from class for DI/testability. Generates IClassName.cs and adds interface implementation to class
• New: organize_usings - Sort and remove unused using directives. Roslyn-powered cleanup with CS8019/CS0105 diagnostics

v1.13.0

• New: preview_split_class / apply_split_class - Split large classes into partial files with smart method grouping
• New: preview_move_type / apply_move_type - Move types to their own files
• New: apply_extract_method - Extract code selection into a new method
• Improved: get_type_members - Now works with ANY type including external (NuGet, System., Microsoft.). Use short name (Solution) or full name (Microsoft.CodeAnalysis.Solution)
• Improved: Tool descriptions with concrete examples for better AI tool selection
• Removed: get_completions, get_signature_help - Replaced by enhanced get_type_members and get_overloads

v1.12.0

• New: get_full_context - Get complete context for a symbol in one call: callers, callees, dependencies, related types
• Improved: Redesigned all tool descriptions for better AI tool selection - priorities, explicit negations, use cases, workflow guidance

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 50+ Roslyn-powered tools:

| Category | Tools | |----------|-------| | 🔍 Navigation | find_references, find_definition, find_callers, find_callees, find_implementations, find_overrides, find_base_members | | 🧠 Understanding | understand_type, understand_method, get_type_info, get_type_members, get_method_body, get_class_hierarchy | | 📁 Structure | get_solution_structure, get_project_structure, get_file_outline, get_types_in_file, find_entry_points, get_dependency_graph | | 🩺 Diagnostics | get_errors, get_warnings, validate_text, find_async_issues, find_performance_issues, find_unused_code | | 🔧 Refactoring | preview_rename, apply_rename, extract_interface, organize_usings, impact_analysis, change_scope, preview_extract_method, suggest_refactorings | | 💡 IntelliSense | get_quick_fixes, get_overloads, get_xml_documentation | | 🔎 Search | find_attribute_usages, find_event_subscribers, find_extension_methods, find_tests_for_type, text_search | | 📊 Metrics | get_code_metrics, analyze_data_flow, get_full_context, get_constructor_parameters |

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

PolyForm Noncommercial 1.0.0 — Free for personal and non-commercial use.

Commercial use requires a separate license. See LICENSE for details.

For commercial licensing, contact: ko-fi.com/yaroslavhorokhov