Roslyn CodeLens MCP Server
A Roslyn-based MCP server that gives AI agents deep semantic understanding of .NET codebases — type hierarchies, call graphs, DI registrations, diagnostics, refactoring, and more.
Hosted deployment
A hosted deployment is available on Fronteir AI.
Features
- find_implementations — Find all classes/structs implementing an interface or extending a class
- find_callers — Find every call site for a method, property, or constructor
- get_type_hierarchy — Walk base classes, interfaces, and derived types
- get_di_registrations — Scan for DI service registrations
- get_project_dependencies — Get the project reference graph
- get_symbol_context — One-shot context dump for any type
- find_reflection_usage — Detect dynamic/reflection-based usage
- find_references — Find all references to any symbol (types, methods, properties, fields, events)
- go_to_definition — Find the source file and line where a symbol is defined
- get_diagnostics — List compiler errors, warnings, and Roslyn analyzer diagnostics
- get_code_fixes — Get available code fixes with structured text edits for any diagnostic
- search_symbols — Fuzzy workspace symbol search by name
- get_nuget_dependencies — List NuGet package references per project
- find_attribute_usages — Find types and members decorated with a specific attribute
- find_circular_dependencies — Detect cycles in project or namespace dependency graphs
- get_complexity_metrics — Cyclomatic complexity analysis per method
- find_naming_violations — Check .NET naming convention compliance
- find_large_classes — Find oversized types by member or line count
- find_unused_symbols — Dead code detection via reference analysis
- get_source_generators — List source generators and their output per project
- get_generated_code — Inspect generated source code from source generators
- get_code_actions — Discover available refactorings and fixes at any position (extract method, rename, inline variable, and more)
- apply_code_action — Execute any Roslyn refactoring by title, with preview mode (returns a diff before writing to disk)
- list_solutions — List all loaded solutions and which one is currently active
- set_active_solution — Switch the active solution by partial name (all subsequent tools operate on it)
- rebuild_solution — Force a full reload of the analyzed solution
- analyze_data_flow — Variable read/write/capture analysis within a statement range (declared, read, written, always assigned, captured, flows in/out)
- analyze_control_flow — Branch/loop reachability analysis within a statement range (start/end reachability, return statements, exit points)
- analyze_change_impact — Show all files, projects, and call sites affected by changing a symbol — combines find_references and find_callers
- get_type_overview — Compound tool: type context + hierarchy + file diagnostics in one call
- analyze_method — Compound tool: method signature + callers + outgoing calls in one call
- get_file_overview — Compound tool: types defined in a file + file-scoped diagnostics in one call
Quick Start
VS Code / Visual Studio (via dnx)
Add to your MCP settings (.vscode/mcp.json or VS settings):
{
"servers": {
"roslyn-codelens": {
"type": "stdio",
"command": "dnx",
"args": ["RoslynCodeLens.Mcp", "--yes"]
}
}
}
Claude Code Plugin
claude install gh:MarcelRoozekrans/roslyn-codelens-mcp
.NET Global Tool
dotnet tool install -g RoslynCodeLens.Mcp
Then add to your MCP client config:
{
"mcpServers": {
"roslyn-codelens": {
"command": "roslyn-codelens-mcp",
"args": [],
"transport": "stdio"
}
}
}
Usage
