Onesown MCP Bridge for Visual Studio
Let your AI assistant understand the code in your running Visual Studio solution.
Onesown MCP Bridge connects MCP-capable assistants, including Codex, to Visual Studio. This extension adds Roslyn analysis using the workspace that Visual Studio has already loaded: the right projects, symbol identities, references and current compiler diagnostics.
This VSIX is the optional Visual Studio component. It requires the separate Onesown MCP Bridge server and an MCP client. Installing the extension alone does not add a chat window or configure an AI assistant.
What the extension adds
Ask your assistant questions like these:
| Feature |
Example question |
| Find source symbols — locate types and members across the loaded solution. |
“Find the OrderService class and open its definition.” |
| Find references — find uses of the exact symbol at a source position, including the selected overload. |
“Where is this method used?” |
| Find callers — identify calling methods and their source locations. |
“Which methods call SaveOrder?” |
| Explore type hierarchies — inspect base types, interfaces, derived classes and implementations. |
“Which classes implement IOrderRepository?” |
| Read live compiler diagnostics — inspect current errors and warnings for a source document without building. |
“Does this file already contain compiler errors?” |
The extension also supplies a Roslyn compiler check before the server requests Hot Reload. This helps catch compiler errors even when Visual Studio's Error List filters hide them. Visual Studio still determines whether a change can be applied.
These are example requests to your assistant, not fixed commands. The assistant translates them into MCP tool calls.
Part of a complete Visual Studio connection
The separate server provides 30 MCP tools in total:
- 24 tools that work without this extension: discover Visual Studio instances, inspect the solution and editor context, open files, build projects or solutions, read output and errors, control the debugger, inspect stack frames and variables, manage breakpoints, and request Hot Reload.
- One availability check: reports whether the extension is connected for the selected Visual Studio window.
- Five analysis tools supplied by this extension: symbols, references, callers, type hierarchies and document diagnostics.
The server remains usable when the extension is absent. Only requests for the five analysis features require it; Hot Reload can use the Visual Studio Error List without the additional Roslyn check.
Getting started
- Download the Windows x64 server ZIP from the Onesown MCP Bridge releases. Extract the entire archive to a permanent folder, for example
D:\Tools\Onesown.VisualStudio.McpBridge.
- Install the .NET 10 Runtime for Windows x64. An installed .NET 10 SDK also supplies the runtime.
- Register the extracted server in your MCP client. For Codex, add or update this entry in
~/.codex/config.toml, using your actual installation path:
[mcp_servers.visualstudio]
command = 'D:\Tools\Onesown.VisualStudio.McpBridge\Onesown.VisualStudio.McpBridge.exe'
startup_timeout_sec = 10
tool_timeout_sec = 600
- Install this extension, restart the target Visual Studio window and open your solution. Reload the MCP connection in your assistant.
Start with “Which Visual Studio instances are open?”, then “Is semantic code analysis connected?” A successful vs_get_semantic_status response contains available: true.
The extension activates in the background when a solution is open. There is no separate command or tool window to start.
Requirements and supported code
- Windows x64 and Visual Studio 2022 17.14+ or Visual Studio 2026, Community, Professional or Enterprise.
- .NET Framework 4.7.2 or later for the in-process extension.
- .NET 10 Runtime x64 for the separate MCP server.
- An MCP client that supports local servers over standard input/output.
- Visual Studio and the MCP server running as the same Windows user at the same permission level.
- A loaded C# or Visual Basic solution for Roslyn analysis.
Source documents such as .cs, .vb and .razor.cs are supported. Mapping generated Razor code back to .razor is not implemented. Document diagnostics cover compiler and semantic diagnostics; the extension does not run every third-party analyzer.
With several Visual Studio windows or worktrees, ask the assistant to target the full solution path. Searches are bounded and report when results are truncated.
Local connection
The extension communicates with the server through a local named pipe restricted to the current Windows user. It has no HTTP listener or separate cloud service. Returned code information goes to your MCP client; any further processing depends on that client's configuration.
Troubleshooting
- Semantic status says
available: false: confirm that this extension is enabled in the target Visual Studio instance, reopen its solution, and check the selected solution path. The server's other tools remain available.
- The assistant cannot connect: check the server path, keep all extracted DLLs beside the executable, verify the .NET 10 Runtime, and reload the client's MCP connection.
- Several solutions are open: provide the full path of the intended solution.
See the project README for the complete feature list, tool parameters, architecture and build instructions.
