MCPHost SDK

The MCPHost SDK allows you to use MCPHost programmatically from Go applications without spawning OS processes.

Installation

go get github.com/mark3labs/mcphost

Basic Usage

package main

import (
    "context"
    "fmt"
    "log"
    
    "github.com/mark3labs/mcphost/sdk"
)

func main() {
    ctx := context.Background()
    
    // Create MCPHost instance with default configuration
    host, err := sdk.New(ctx, nil)
    if err != nil {
        log.Fatal(err)
    }
    defer host.Close()
    
    // Send a prompt
    response, err := host.Prompt(ctx, "What is 2+2?")
    if err != nil {
        log.Fatal(err)
    }
    
    fmt.Println(response)
}

Configuration

The SDK behaves identically to the CLI:

• Loads configuration from ~/.mcphost.yml by default
• Creates default configuration if none exists
• Respects all environment variables (MCPHOST_*)
• Uses the same defaults as the CLI

Options

You can override specific settings:

host, err := sdk.New(ctx, &sdk.Options{
    Model:        "ollama/llama3",            // Override model
    SystemPrompt: "You are a helpful bot",   // Override system prompt
    ConfigFile:   "/path/to/config.yml",     // Use specific config file
    MaxSteps:     10,                        // Override max steps
    Streaming:    true,                      // Enable streaming
    Quiet:        true,                      // Suppress debug output
})

Advanced Usage

With Tool Callbacks

Monitor tool execution in real-time:

response, err := host.PromptWithCallbacks(
    ctx,
    "List files in the current directory",
    func(name, args string) {
        fmt.Printf("Calling tool: %s\n", name)
    },
    func(name, args, result string, isError bool) {
        if isError {
            fmt.Printf("Tool %s failed: %s\n", name, result)
        } else {
            fmt.Printf("Tool %s succeeded\n", name)
        }
    },
    func(chunk string) {
        fmt.Print(chunk) // Stream output
    },
)

Session Management

Maintain conversation context:

// First message
host.Prompt(ctx, "My name is Alice")

// Second message (remembers context)
response, _ := host.Prompt(ctx, "What's my name?")
// Response: "Your name is Alice"

// Save session
host.SaveSession("./session.json")

// Load session later
host.LoadSession("./session.json")

// Clear session
host.ClearSession()

API Reference

Types

• MCPHost - Main SDK type
• Options - Configuration options
• Message - Conversation message
• ToolCall - Tool invocation details

Methods

• New(ctx, opts) - Create new MCPHost instance
• Prompt(ctx, message) - Send message and get response
• PromptWithCallbacks(ctx, message, ...) - Send message with progress callbacks
• LoadSession(path) - Load session from file
• SaveSession(path) - Save session to file
• ClearSession() - Clear conversation history
• GetSessionManager() - Get session manager for advanced usage
• GetModelString() - Get current model string
• Close() - Clean up resources

Environment Variables

All CLI environment variables work with the SDK:

• MCPHOST_MODEL - Override model
• ANTHROPIC_API_KEY - Anthropic API key
• OPENAI_API_KEY - OpenAI API key
• GEMINI_API_KEY - Google API key
• etc.

License

Same as MCPHost CLI