MarcelRoozekrans/roslyn-codelens-mcp

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 ()), 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