roslyn-codelens-mcp

# Roslyn CodeLens MCP Server

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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.

<a href="https://glama.ai/mcp/servers/MarcelRoozekrans/roslyn-codelens-mcp">
  <img width="380" height="200" src="https://glama.ai/mcp/servers/MarcelRoozekrans/roslyn-codelens-mcp/badge" alt="roslyn-codelens-mcp MCP server" />
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<!-- mcp-name: io.github.MarcelRoozekrans/roslyn-codelens -->

---

## Hosted deployment

A hosted deployment is available on [Fronteir AI](https://fronteir.ai/mcp/marcelroozekrans-roslyn-codelens-mcp).

## 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. Pass `fromProject` to learn whether *that* project can actually reach each option — it honours `InternalsVisibleTo`, so it answers "can my test project call this internal constructor?"
- **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
- **get_exception_flow** — What exceptions can escape a method: walks callees depth-bounded, propagates each throw up through every enclosing try/catch, and reports what still escapes with its propagation path; metadata callees contribute their documented exceptions
- **find_throw_sites** — Every place an exception type is thrown, optionally including derived types; rethrows flagged
- **find_catch_blocks** — Every catch for a type, optionally via base clauses; flags filtered, rethrowing, and empty (swallowing) handlers
- **find_references** — Find all references to any symbol (types, methods, properties, fields, events), each tagged with a kind (`read`, `write`, `readwrite`, `invocation`, `method_group`, `object_creation`, `cast`, `type_check`, `typeof`, `base_type`, `type_constraint`, `type_argument`, `declaration`, `attribute`, `nameof`, `xml_doc`) and reported per occurrence with a column; filter server-side with `kinds` (e.g. `["write","readwrite"]` for mutation sites)
- **go_to_definition** — Find the source file and line where a symbol is defined
- **get_method_source** — Full declaration source (XML docs, attributes, signature, body — original formatting) for one or many members by name in a single call: methods (all overloads), constructors, properties, indexers, fields, events; per-item statuses (`ok`/`notFound`/`ambiguous`/`metadata`/`unsupportedKind`) so a batch never fails wholesale
- **resolve_stack_trace** — Map a pasted .NET stack trace to file/line/symbol, undoing compiler name mangling (async/iterator state machines, lambdas, local functions, generic arity); handles inner-exception chains, log-prefixed lines, and Demystifier traces
- **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
- **check_architecture** — Enforce layering rules you supply (`forbid` and `allowOnly`) against the real semantic type graph rather than `using` directives; violations are grouped per boundary with a reference count and example sites
- **get_complexity_metrics** — Cyclomatic complexity, cognitive complexity and max nesting depth per member (methods, constructors, properties, indexers, operators). Cyclomatic counts paths and starts at 1; cognitive measures how hard the code is to follow and starts at 0. `metric` picks which one the threshold and sort use — cognitive is the better refactoring-priority signal, cyclomatic the better test-budget one
- **find_naming_violations** — Check .NET naming convention compliance
- **find_async_violations** — Sync-over-async, `async void` misuse, missing awaits, fire-and-forget tasks; per-violation report with severity
- **find_disposable_misuse** — `IDisposable`/`IAsyncDisposable` instances not wrapped in `using`/`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)
- **rename_symbol** — Solution-wide safe rename of a type or member via Roslyn's Renamer, with preview mode, conflict reporting, and a freshness check against on-disk edits
- **change_signature** — Add, remove, and reorder a method's parameters and rewrite every call site; handles named/optional arguments, `params` and extension methods, and reports the overrides and interface implementations it cascaded to
- **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 a `taskId` to poll
- **get_task_status** — Get the current