VFS
Reduce AI agent token usage by 98% via Virtual Function Signatures. MCP server for Cursor & Claude Desktop. Supports Go, TypeScript, Python, Rust, Java, Swift, Kotlin, C# and more.
What is VFS?
VFS is a Model Context Protocol (MCP) server that allows AI assistants like Claude, Cursor, and VS Code to reduce ai agent token usage by 98% via virtual function signatures. mcp server for cursor & claude desktop. supports go, typescript, python, rust, java, swift, kotlin, c# and more.
Reduce AI agent token usage by 98% via Virtual Function Signatures. MCP server for Cursor & Claude Desktop. Supports Go, TypeScript, Python, Rust, Java, Swift, Kotlin, C# and more.
This server falls under the Developer Tools and Coding Agents categories on MCPgee, the world's largest MCP server directory with 33,000+ servers.
Features
- Reduce AI agent token usage by 98% via Virtual Function Sign
Use Cases
Maintainer
Works with
Installation
Manual Installation
npx vfsConfiguration
Configuration Details
claude_desktop_config.json
Performance
Response Metrics
Resource Usage
How to Set Up and Use VFS
VFS (Virtual Function Signatures) is an MCP server that dramatically reduces AI agent token consumption by providing only function signatures and type information instead of full source files when an AI needs to understand a codebase. It supports 17 programming languages including Go, TypeScript, Python, Rust, Java, Swift, Kotlin, and C#. Security and development teams use it to let AI assistants navigate large monorepos efficiently without exhausting context windows.
Prerequisites
- Go 1.21+ installed (for building from source) or use pre-built binaries from GitHub Releases
- An MCP-compatible client such as Claude Desktop or Cursor
- A codebase in any of the 17 supported languages to index
- Docker (optional, for containerized deployment)
Install the vfs binary
Build and install the vfs binary from source using the Go toolchain. Alternatively, download a pre-built release binary for your OS from the GitHub Releases page.
go install ./cmd/vfsVerify the installation
Confirm vfs is installed and accessible on your PATH by checking the version.
vfs --versionStart the MCP server
Launch vfs in MCP server mode using stdio transport so your MCP client can connect to it. The `vfs up` command starts it as a background process.
vfs upConfigure your MCP client
Add vfs to your Claude Desktop or Cursor MCP configuration. The server runs as a stdio process pointing to your project directory.
{
"mcpServers": {
"vfs": {
"command": "vfs",
"args": ["mcp"]
}
}
}Test token savings with a search
Use the search tool to locate function signatures by name or pattern, and check cumulative savings with the stats command.
# Search for a function pattern
vfs . -f HandleLogin
# View token savings analytics
vfs statsVFS Examples
Client configuration
Claude Desktop configuration to run the VFS MCP server in stdio mode.
{
"mcpServers": {
"vfs": {
"command": "vfs",
"args": ["mcp"]
}
}
}Prompts to try
Example prompts to use with the VFS MCP server in Claude Desktop or Cursor.
- "Show me all exported functions in the /src/auth directory"
- "Find function signatures matching 'Handler' in the project"
- "What functions are available in the payments module?"
- "List all supported programming languages"
- "Extract signatures from /src/api/routes.ts"Troubleshooting VFS
vfs command not found after go install
Ensure your Go bin directory is on your PATH. Run `export PATH=$PATH:$(go env GOPATH)/bin` and add it to your shell profile (~/.bashrc or ~/.zshrc).
Functions from a specific file are not showing up
Verify the file uses one of the 17 supported languages and that the functions are exported (e.g., capitalized in Go, or use `export` keyword in TypeScript). Run `vfs list_languages` to confirm language support.
MCP client cannot connect to vfs server
Ensure the vfs binary path in your MCP config is absolute or that vfs is on the system PATH accessible to the client process. Use `which vfs` to get the full path and specify it explicitly in the `command` field.
Frequently Asked Questions about VFS
What is VFS?
VFS is a Model Context Protocol (MCP) server that reduce ai agent token usage by 98% via virtual function signatures. mcp server for cursor & claude desktop. supports go, typescript, python, rust, java, swift, kotlin, c# and more. It connects AI assistants to external tools and data sources through a standardized interface.
How do I install VFS?
Follow the installation instructions on the VFS GitHub repository. Clone the repo, install dependencies, and add the server config to your AI client.
Which AI clients work with VFS?
VFS works with all major MCP-compatible AI clients including Claude Desktop, Claude Code, Cursor, VS Code (GitHub Copilot), Windsurf, and Cline.
Is VFS free to use?
Yes, VFS is open source and available under the MIT license. You can use it freely in both personal and commercial projects.
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Quick Config Preview
Add this to your claude_desktop_config.json or .cursor/mcp.json
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