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.

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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
• find_event_subscribers — Every += / -= site for an event symbol, with resolved handler and subscribe/unsubscribe tag
• find_tests_for_symbol — List xUnit/NUnit/MSTest methods that exercise a production symbol; opt-in transitive walk through helpers
• get_test_summary — Per-project inventory of test methods with framework, attribute kind, data-row count, location, and production symbols referenced
• find_uncovered_symbols — Public methods and properties no test transitively reaches; sorted by cyclomatic complexity for prioritization
• generate_test_skeleton — Emit a compilable test-class skeleton (as text) for a method or type. Auto-detects xUnit/NUnit/MSTest; surfaces constructor dependencies as TodoNotes; returns a suggested file path. Closes the loop with find_uncovered_symbols
• get_type_hierarchy — Walk base classes, interfaces, and derived types
• get_di_registrations — Scan for DI service registrations. Reads generic (AddSingleton<IFoo, Foo>()), single-generic, typeof pair and factory-lambda forms
• get_instantiation_options — "How do I construct this type?" in one call: constructors with full parameter detail, static factory methods declared anywhere in the solution (including on a separate factory type), DI registrations, and required members.