Give your AI assistant full control over Visual Studio — code analysis, debugging, UI automation, and more.

Make AI coding assistants actually useful for professional C# development.

Platform: Windows only | Language: C# only | Requirements: Windows 10/11, Visual Studio 2022 (17.9+), any MCP-compatible AI assistant

Demo Video

https://www.youtube.com/watch?v=skvnHbm2lpk

https://www.youtube.com/watch?v=6d6Kx-MnXOc

https://www.youtube.com/watch?v=b3aIBrVaaQo

Quick Start

Install from Visual Studio Marketplace
Open your C# solution in Visual Studio
Go to View → Other Windows → RoslynMCP Dashboard
Copy the connection command for your AI assistant (Claude Code, Codex, Copilot, or Cursor)
Ask your AI to explore all available tools — warning: it may refuse to work without them ever again 😄

⚠️ The path is unique per VS installation — always copy from the Dashboard, not from examples.

Multiple VS instances: Each Visual Studio window runs its own MCP server. AI auto-connects to the one matching your working directory.

Tip: Create skills (slash commands) for the tools you use most — this dramatically improves tool selection and output quality.

Configuration Examples

Open the RoslynMCP Dashboard in Visual Studio (View → Other Windows → RoslynMCP Dashboard) and copy the connection command for your AI tool.

⚠️ The path is unique per VS installation — always copy from the Dashboard, not from examples below.

Claude Code / Codex:

claude mcp add roslyn -- "C:\Users\YOU\...\Proxy\RoslynMcp.Proxy.exe"
codex mcp add roslyn -- "C:\Users\YOU\...\Proxy\RoslynMcp.Proxy.exe"

Works with any AI client that supports the Model Context Protocol.

Features

RoslynMCP includes a 30-day free trial. After the trial period, a license is required to continue using the tools.

Core Features

Roslyn Code Analysis

160+ tools loaded on-demand via search_tools → call_tool
Navigation: find_references, find_definition, find_callers, find_callees, find_implementations, find_overrides
Understanding: understand_type, understand_method, get_type_info, get_type_members, get_method_body
Diagnostics: get_errors, get_warnings, validate_text, find_async_issues, find_performance_issues
Refactoring: apply_rename, extract_interface, organize_usings, apply_split_class, apply_extract_method
Structure: get_solution_structure, get_project_structure, get_file_outline, get_dependency_graph

OOP C# Programming (`cs` tool)

86 actions for object-oriented C# programming directly through Roslyn API — no text editing, no file I/O
Create/update/delete types, members, constructors, properties, events, attributes
Statement-level editing inside method bodies at any nesting depth (if/for/try/switch blocks)
Expression builders, batch mode, block path navigation (Type.Method.if[0].else)
Every mutation returns instant Roslyn diagnostics — no build needed to catch errors

Visual Studio IDE Control

vs — 40 IDE actions: build, debug (start/stop/step/breakpoints), file operations, find/replace, deploy, bookmarks, run_tests, configuration
vs_query — 25 IDE queries: solution, projects, errors, build output, debug state, locals, callstack, threads, expressions, editor context, bookmarks, tests, test_results
vs_query editor_context — cursor position, selected text, word at cursor, surrounding code, breakpoint status, debug value + Roslyn semantic context (method, class, namespace, scope chain, symbol info, diagnostics)
bookmark_set / bookmark_next / bookmark_prev / bookmark_clear_all — AI sets labeled bookmarks, navigates between them, user sees them in VS editor margins
debug_monitor — live state of debugged app: windows, dialogs, UI elements. Blocking waitFor eliminates polling
list_instances / switch_instance — manage multiple VS instances from one AI session
Auto-schema on errors — when AI sends wrong parameters, the error response includes the correct JSON schema so AI self-corrects on next attempt

Test Runner

vs { "action": "run_tests" } — run all tests via Test Explorer (non-blocking, background)
vs { "action": "run_tests", "options": {"failedOnly": true} } — re-run only failed tests
vs { "action": "stop_tests" } — cancel running tests
vs_query { "what": "test_results" } — get results: passed/failed counts, error messages with file:line
vs_query { "what": "tests" } — discover all test methods via Roslyn ([Fact]/[Test]/[TestMethod] attributes)
find_tests_for_type — find unit tests targeting a specific type across test projects
Full TDD cycle: run → check errors → fix → re-run failed → all green

Desktop Automation & UI Testing

screen (23 actions) — screenshots (full screen, window, region), mouse (click/double-click/move/scroll), keyboard input (Unicode, hotkeys, combos), window/process management, clipboard, screen info
ui_find / ui_invoke / ui_tree — Windows UI Automation: find elements by name/automationId, invoke buttons, toggle checkboxes, select items, double-click
ui_set_value / ui_get_value / ui_table — read/write form fields, read data grids
ui_expand / ui_select — expand/collapse tree nodes, select items in lists and combo boxes
Works with WinForms, WPF, Win32 apps. Partial support for Electron apps (Teams, Slack, WhatsApp).

BlazorPilot — Blazor & Web UI Automation (NEW)

AI-driven browser automation via Chrome DevTools Protocol (CDP) + Roslyn code analysis. Full DevTools access with Roslyn C# integration. No screenshots needed — AI reads the page as structured text and interacts with elements directly.

Works with:

Blazor Desktop (WebView2 / MAUI / WPF) — add to your launchSettings.json:

"environmentVariables": {
    "WEBVIEW2_ADDITIONAL_BROWSER_ARGUMENTS": "--remote-debugging-port=9222"
}

Blazor Server / WASM — launch browser with --remote-debugging-port=9222 and your app URL
Any website in Chrome/Edge — launch with chrome --remote-debugging-port=9222 --user-data-dir=<temp> <url>

35 actions in one blazor tool:

Category	Actions
Roslyn analysis	`inspect` (.razor components, events, @bind, state, methods → C# file:line), `list_pages`
UI actions	`click`, `click_by_text`, `type`, `press_key`, `select`, `hover`, `scroll`, `check/uncheck`, `wait`, `focus`, `clear`
Page observation	`accessibility_tree` (with HTML snippets), `snapshot`, `screenshot` (full page or element)
DevTools	`console` logs, `network` requests with status codes, `cookies`, `storage`
CSS & inspection	`css` (get/set styles), `element_state`, `highlight`, `count`
Emulation	`viewport` (mobile/tablet), `emulate` (dark/light mode), `performance` metrics
Navigation	`navigate`, `eval` (JavaScript), `connect`, `disconnect`

Key capabilities:

Real browser clicks via CDP — works with Blazor EventCallbacks (not just JS .click())
click_by_text with smart overlay/modal detection — finds buttons in popups first
Enhanced accessibility_tree includes HTML snippets for interactive elements
inspect combines Roslyn static analysis with runtime browser state — AI sees both the UI and the C# handler behind each button
console and network capture logs and HTTP requests in real-time with status codes and errors

Memory & Knowledge Base

memory_* (17 tools) — persistent cross-session memory with vector search (ONNX)
kb_* (8 tools) — permanent knowledge base with semantic + full-text search

Dashboard

Tool window in VS (View → Other Windows → RoslynMCP Dashboard)
License status with activation (trial countdown, license key input, Buy button)
Connection configs for Claude Code, Codex, GitHub Copilot, Cursor — copy with one click
Tabs: Workflows editor, Memory editor, Knowledge Base editor, Debug Monitor (live windows/elements/events)

Experimental Features

These features are functional but still being improved and tested.

Claude Chat Panel

Built-in Claude Code chat directly in Visual Studio (View → Other Windows → Claude Chat)
Adapted from Claude Code for VS Code extension — React UI running in WebView2
RoslynMCP tools are automatically connected via --mcp-config — no manual setup needed
Bundled Roslyn skills are included with the extension at Skills/.claude/skills/ inside the VSIX. To customize, copy them to your project's .claude/skills/ directory or edit them for use with Claude Code in PowerShell

Markdown Tool

md — structured .md editing & multi-file search (18 actions)
- Single-file: toc, tree, read, read_section, search, edit_section, insert_section, append, delete_section, replace
- Tree-first creation: create_doc, add_node, bulk_create, rename_node, move_node — create documents as a tree, auto heading levels
- Multi-file index: index, search_all, stats — hybrid search: SQLite FTS5 (keywords) + ONNX embeddings (semantic)
- On-demand indexing: only re-indexes changed files, auto-cleans deleted, auto-reindex on edit

DevGraph

graph_* (10 tools) — track changes, dependencies, cause-effect during development
graph_build_from_type — auto-build dependency graph from Roslyn semantic model
graph_track_change / graph_track_dependency / graph_track_cause — record changes and relationships
graph_get_impact — what breaks if I change X?
graph_get_dependencies / graph_get_path / graph_get_history — explore connections and evolution
graph_visualize — export as Mermaid or DOT diagram

AI Workflow Engine

wf_* (27 tools) — reusable step-by-step instructions for AI
AI follows steps, annotates results, learns from mistakes
Step types: execute, verify, wait, call_case (nested), ai_freeform
Background watchers for windows, UI elements, processes
Progress tracking and run history

Troubleshooting

Extension not loading

Check Visual Studio Output window for errors
Verify extension is enabled in Extensions → Manage Extensions

AI assistant not connecting

Ensure Visual Studio has a solution open
Open the RoslynMCP Dashboard (View → Other Windows → RoslynMCP Dashboard) — status should show "Running"
Copy the connection command from the Dashboard for your AI tool

First connection fails (e.g. in VS Copilot logs): This is normal — the MCP server starts before the extension finishes loading. The automatic retry connects successfully. No action needed.

Multiple VS instances or wrong project: Ask your AI assistant: "List all active RoslynMCP instances and switch to my current project." The assistant will use list_instances and switch_instance to reconnect to the right Visual Studio instance.

No tools available

Make sure you copied the correct configuration for your AI assistant
Restart your AI assistant after configuration changes

Data Storage

RoslynMCP creates databases in .roslyn-mcp/ inside your solution directory:

File	Contents
`memory.db`	Memory, Knowledge Base, DevGraph, configuration
`testcases.db`	AI Workflow Engine: workflows, steps, run history
`md_index.db`	Markdown multi-file FTS5 index (sections, hierarchy, full-text search)

License data is stored in %AppData%/RoslynMcp/.

RoslynMCP vs Other AI IDE Integrations

All major AI coding tools (Claude Code, GitHub Copilot, Cursor) provide code understanding, inline diffs, terminal access, and agent capabilities. RoslynMCP is different in two specific ways:

Direct Roslyn Compiler Access

Other tools analyze code through text search or LLM context windows. RoslynMCP connects to the same Roslyn compiler API that powers Visual Studio IntelliSense:

Capability	Text/LLM-based tools	RoslynMCP
Find references	Text search — may miss overloads, generics, partial classes	`find_references` — compiler-resolved, 100% accurate
Understand type	LLM reads source text	`understand_type` — members, hierarchy, callers from compiled model
Call graph	Not available	`get_full_context` — recursive call tree up & down
Refactoring	Generate text diff	`apply_rename`, `apply_extract_method`, `apply_split_class` — via Roslyn code actions
Edit C# code	Generate text diff, hope it compiles	`cs` tool — 86 OOP actions with instant Roslyn diagnostics
Symbol at cursor	IDE-internal or unavailable	`editor_context` — resolved type, kind, full name from semantic model
Data flow	Not available	`analyze_data_flow`, `analyze_operations`

Full Visual Studio Debugger Control

No other AI tool gives the AI model direct programmatic access to the Visual Studio debugger:

vs start_debug / stop_debug — launch and stop debugging sessions
vs step_over / step_into / step_out — sync stepping, returns new state + locals automatically
vs breakpoint_add — conditional breakpoints, function breakpoints
vs_query locals / callstack / expression — inspect runtime state
debug_monitor — live window/dialog tracking with blocking waitFor

This enables the self-development loop: code → build → set breakpoint → debug → inspect → fix — all controlled by AI.

Scaffolding vs Refactoring

When creating files from scratch, text-based tools write entire files in one call. RoslynMCP's cs tool trades raw speed for compile-time safety — every operation is validated by Roslyn before saving:

Task	Text-based tools	RoslynMCP	Faster
Create new class	`Write` — one call, instant	`cs batch` — create + add members + validate diagnostics	Text-based
Create 5 classes	5 parallel `Write` calls	5 parallel `cs batch` calls — same parallelism, plus compile check	Text-based
Add method to existing class	`Edit` — text diff, may break syntax	`cs add_method` — Roslyn-parsed, guaranteed valid	~Equal
Rename across solution	`Edit` multiple files, hope nothing breaks	`apply_rename` — compiler-resolved, updates all references	RoslynMCP
Move statements inside method	Read → understand nesting → Edit	`cs update_statement` with block path — precise targeting	~Equal
Find all usages	`grep` — misses overloads, generics	`find_references` — 100% accurate from compiler	RoslynMCP
Refactor + verify no errors	Edit → build → fix errors → repeat	`cs` edit → instant diagnostics → done in one pass	RoslynMCP

Trade-off: Scaffolding from scratch is slightly slower because each cs batch call validates syntax via Roslyn compiler. The payoff: zero broken builds, zero missing references, zero syntax errors in generated code. For refactoring and multi-file changes, RoslynMCP eliminates the trial-and-error cycle that text-based tools require.

License

Starting from v1.18.6, RoslynMCP includes a 30-day free trial. After the trial, a subscription is required.

Trial: 30 days, full access, no registration needed
Subscription: available at roslynmcp.lemonsqueezy.com
License key: enter in RoslynMCP Dashboard (View → Other Windows → RoslynMCP Dashboard)
Previous versions (v1.18.4 and earlier) remain fully free

For enterprise licensing or questions, contact via Visual Studio Marketplace.

Tired of typing prompts manually? 🎤

Try Murmur — offline voice-to-text for Windows. Fast, private, no cloud. 👉 https://murmurvt.com/

RoslynMCP - Roslyn MCP Server for C# Projects

Yaroslav Horokhov

Give your AI assistant full control over Visual Studio — code analysis, debugging, UI automation, and more.

Demo Video

Quick Start

Configuration Examples

Features

Core Features

Roslyn Code Analysis

OOP C# Programming (`cs` tool)

Visual Studio IDE Control

Test Runner

Desktop Automation & UI Testing

BlazorPilot — Blazor & Web UI Automation (NEW)

Memory & Knowledge Base

Dashboard

Experimental Features

Claude Chat Panel

Markdown Tool

DevGraph

AI Workflow Engine

Troubleshooting

Extension not loading

AI assistant not connecting

No tools available

Data Storage

RoslynMCP vs Other AI IDE Integrations

Direct Roslyn Compiler Access

Full Visual Studio Debugger Control

Scaffolding vs Refactoring

License

Tired of typing prompts manually? 🎤

RoslynMCP - Roslyn MCP Server for C# Projects

Yaroslav Horokhov

Give your AI assistant full control over Visual Studio — code analysis, debugging, UI automation, and more.

Demo Video

Quick Start

Configuration Examples

Features

Core Features

Roslyn Code Analysis

OOP C# Programming (cs tool)

Visual Studio IDE Control

Test Runner

Desktop Automation & UI Testing

BlazorPilot — Blazor & Web UI Automation (NEW)

Memory & Knowledge Base

Dashboard

Experimental Features

Claude Chat Panel

Markdown Tool

DevGraph

AI Workflow Engine

Troubleshooting

Extension not loading

AI assistant not connecting

No tools available

Data Storage

RoslynMCP vs Other AI IDE Integrations

Direct Roslyn Compiler Access

Full Visual Studio Debugger Control

Scaffolding vs Refactoring

License

Tired of typing prompts manually? 🎤

OOP C# Programming (`cs` tool)