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
- 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
- get_project_dependencies — Get the project reference graph
- get_symbol_context — One-shot context dump for any type
- get_public_api_surface — Enumerate every public/protected type and member in production projects; flat, deterministically-sorted list suitable for API review or breaking-change baselines.
- find_breaking_changes — Diff the current API against a baseline JSON or DLL; report removed members, kind changes, and accessibility changes with Breaking/NonBreaking severity.
- 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_obsolete_usage — Every
[Obsolete]call site grouped by deprecation message and severity, errors first; for planning migrations - 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_async_violations — Sync-over-async,
async voidmisuse, missing awaits, fire-and-forget tasks; per-violation report with severity - find_disposable_misuse —
IDisposable/IAsyncDisposableinstances not wrapped inusing/await using/returned/assigned to field; severity error/warning per violation. - find_large_classes — Find oversized types by member or line count
- find_god_objects — Types combining high size with high cross-namespace coupling; sharper signal than raw size for SRP violations
- find_unused_symbols — Dead code detection via reference analysis. Auto-filters test methods (xUnit/NUnit/MSTest), MCP tool entry points, source-generator output, MEF-composed services, and interop-laid-out fields; filter counts surface in
summary.filteredOut - get_project_health — Composite audit aggregating 7 quality dimensions per project (complexity, large classes, naming, unused symbols, reflection, async violations, disposable misuse) with counts and top-N hotspots inline
- get_source_generators — List source generators and their output per project
- get_generated_code — Inspect generated source code from source generators
- inspect_external_assembly — Browse types, members, and XML docs from closed-source NuGet packages and referenced assemblies
- peek_il — Decompile any method to ilasm-style IL bytecode from closed-source or generated assemblies
- 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)
- load_solution — Load an additional .sln/.slnx at runtime and make it the active solution
- unload_solution — Unload a loaded solution to free memory
- rebuild_solution — Force a full reload of the analyzed solution
- start_background_task — Queue a long-running tool (currently
rebuild_solution) to run in the background; returns ataskIdto poll - get_task_status — Get the current status, result, or error of a background task by its
taskId - list_running_tasks — List background tasks running or completed within the last 5 minutes
- trust_solution — Authorize a solution to run Roslyn analyzers (required before
get_diagnosticswithincludeAnalyzers: true) - list_trusted_paths — Inspect the persistent trust store + session-trusted solutions
- revoke_trust — Revoke a previously-granted trust for a solution path
- 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_overloads — Every overload of a method/constructor (source + metadata) with full parameter and modifier detail in one call
- get_operators — Every user-defined operator and conversion operator on a type (source + metadata) with kind, signature, parameters, and source location. Includes synthesized record equality and .NET 7+ checked variants
- get_call_graph — Transitive caller/callee graph for a method, depth-bounded with cycle detection
- get_file_overview — Compound tool: types defined in a file + file-scoped diagnostics in one call
