Cobra CLI to MCP server library

Transform any Cobra CLI into an MCP server

Ophis automatically converts your Cobra commands into MCP tools, and provides CLI commands for integration with Claude Desktop, VSCode, and Cursor.

Quick Start

Install

go get github.com/njayp/ophis

Add to your CLI

package main

import (
    "os"
    "github.com/njayp/ophis"
)

func main() {
    rootCmd := createMyRootCommand()
    rootCmd.AddCommand(ophis.Command(nil))

    if err := rootCmd.Execute(); err != nil {
        os.Exit(1)
    }
}

Enable in Claude Desktop, VSCode, or Cursor

# Claude Desktop
./my-cli mcp claude enable
# Restart Claude Desktop

# VSCode (requires Copilot in Agent Mode)
./my-cli mcp vscode enable

# Cursor
./my-cli mcp cursor enable

Your CLI commands are now available as MCP tools!

Stream over HTTP

Expose your MCP server over HTTP for remote access:

./my-cli mcp stream --host localhost --port 8080

Commands

The ophis.Command(nil) adds these subcommands to your CLI (the default command name is mcp, configurable via Config.CommandName):

mcp
├── start            # Start MCP server on stdio
├── stream           # Stream MCP server over HTTP
├── tools            # Export available MCP tools as JSON
├── claude
│   ├── enable       # Add server to Claude Desktop config
│   ├── disable      # Remove server from Claude Desktop config
│   └── list         # List Claude Desktop MCP servers
├── vscode
│   ├── enable       # Add server to VSCode config
│   ├── disable      # Remove server from VSCode config
│   └── list         # List VSCode MCP servers
└── cursor
    ├── enable       # Add server to Cursor config
    ├── disable      # Remove server from Cursor config
    └── list         # List Cursor MCP servers

Configuration

Control which commands and flags are exposed as MCP tools using selectors. By default, all commands and flags are exposed (except hidden/deprecated).

config := &ophis.Config{
    Selectors: []ophis.Selector{
        {
            CmdSelector: ophis.AllowCmdsContaining("get", "list"),
            LocalFlagSelector: ophis.ExcludeFlags("token", "secret"),
            InheritedFlagSelector: ophis.NoFlags,  // Exclude persistent flags

            // Middleware wraps command execution
            Middleware: func(ctx context.Context, req *mcp.CallToolRequest, in ophis.ToolInput, next func(context.Context, *mcp.CallToolRequest, ophis.ToolInput) (*mcp.CallToolResult, ophis.ToolOutput, error)) (*mcp.CallToolResult, ophis.ToolOutput, error) {
                ctx, cancel := context.WithTimeout(ctx, time.Minute)
                defer cancel()
                return next(ctx, req, in)
            },
        },
    },
}

rootCmd.AddCommand(ophis.Command(config))

Custom Command Name

By default the ophis command is named mcp. If your CLI already uses mcp for something else, set CommandName to avoid the collision:

config := &ophis.Config{
    CommandName: "agent",
}

rootCmd.AddCommand(ophis.Command(config))

The command tree, editor config (enable/disable), and internal filters all use the configured name automatically.

Default Environment Variables

Editors launch MCP server subprocesses with a minimal environment. On macOS this means a PATH of just /usr/bin:/bin:/usr/sbin:/sbin, so tools like helm, kubectl, or docker installed via mise/homebrew/nix won't be found. Use DefaultEnv to capture the current PATH (or any other variables) at enable time:

config := &ophis.Config{
    DefaultEnv: map[string]string{
        "PATH": os.Getenv("PATH"),
    },
}

rootCmd.AddCommand(ophis.Command(config))

These are merged into the editor config written by enable. User-provided --env values take precedence on conflict.

See docs/config.md for detailed configuration options.

How It Works

Ophis bridges Cobra commands and the Model Context Protocol:

1. Command Discovery: Recursively walks your Cobra command tree
2. Schema Generation: Creates JSON schemas from command flags and arguments (docs/schema.md)
3. Tool Execution: Spawns your CLI as a subprocess and captures output (docs/execution.md)

Contributing

Contributions welcome! See CONTRIBUTING.md.