mcp-server-developer-tool

# Modular MCP Server This is a Go implementation of the Model Context Protocol (MCP) server using the `github.com/metoro-io/mcp-golang` library, restructured in a modular way. ## Project Structure ``` mcp-server/ ├── cmd/ │ └── mcp-server/ │ └── main.go # Entry point ├── internal/ │ ├── config/ │ │ └── config.go # Server configuration │ ├── server/ │ │ ├── server.go # MCP server implementation │ │ └── server_test.go # Server tests │ ├── tools/ │ │ ├── tool.go # Tool interface │ │ ├── execute.go # Execute shell command tool │ │ ├── showfile.go # Show file tool │ │ ├── searchfile.go # Search in file tool │ │ └── writefile.go # Write file tool │ └── utils/ │ └── response.go # Common response utilities ├── go.mod ├── go.sum └── README.md ``` ## Building and Running ```bash # Build the server cd cmd/mcp-server go build -o mcp-server # Run the server ./mcp-server ``` ## Security Features The server now includes a path restriction system to limit file operations to specified directories. ### Configuring Allowed Paths You can configure allowed paths in several ways: #### 1. Using Command-line Flags ```bash # Allow operations only in specific directories ./mcp-server --paths=/home/user/safe:/tmp/workspace # Explicitly deny specific paths even if within allowed paths ./mcp-server --paths=/home/user --deny-paths=/home/user/.ssh:/home/user/credentials ``` #### 2. Using Environment Variables ```bash # Set allowed paths export MCP_ALLOWED_PATHS=/home/user/safe:/tmp/workspace # Set denied paths export MCP_DENIED_PATHS=/home/user/.ssh:/home/user/credentials # Run the server ./mcp-server ``` #### 3. Programmatically You can also create a custom configuration programmatically: ```go cfg := config.DefaultConfig() cfg.AddAllowedPath("/path/to/allow") cfg.AddDeniedPath("/path/to/deny") server, err := server.NewServerWithConfig(cfg) ``` ### Default Behavior - If no paths are specified, the server defaults to allowing only the current working directory. - Common sensitive directories like `.git` and `.env` are automatically added to the deny list. ### Shell Command Security For the `execute_shell_command` tool: - Commands are restricted to a whitelist of common utilities - Custom executable paths are checked against the allowed paths configuration - Working directories must be within allowed paths ## Adding New Tools To add a new tool: 1. Create a new file in the `internal/tools` directory 2. Implement the `Tool` interface 3. Optionally implement the `ConfigAware` interface if your tool needs access to server configuration 4. Register the tool in `cmd/mcp-server/main.go` Example: ```go // internal/tools/newtool.go package tools import ( "github.com/metoro-io/mcp-golang" "mcp-server/internal/config" "mcp-server/internal/utils" ) type NewToolArgs struct { // Tool arguments } type NewTool struct{ config *config.ServerConfig } func NewNewTool() *NewTool { return &NewTool{} } // Implement ConfigAware interface func (t *NewTool) SetConfig(cfg *config.ServerConfig) { t.config = cfg } func (t *NewTool) Name() string { return "new_tool" } func (t *NewTool) Description() string { return "Description of the new tool" } func (t *NewTool) Execute(args NewToolArgs) (*mcp.ToolResponse, error) { // Access configuration if needed if t.config != nil { // Use configuration for security checks } // Tool implementation return utils.CreateSuccessResponse(result), nil } ``` ## Testing ```bash go test ./... ```