How to Use the OpenAI Server with big-AGI

This guide shows you how to set up and configure the gomcptest OpenAI-compatible server to work with big-AGI, a popular open-source web client for AI assistants.

Prerequisites

• A working installation of gomcptest
• The OpenAI-compatible server running (see the OpenAI Server tutorial)
• Node.js (version 18.17.0 or newer)
• Git

Why Use big-AGI with gomcptest?

big-AGI provides a polished, feature-rich web interface for interacting with AI models. By connecting it to the gomcptest OpenAI-compatible server, you get:

• A professional web interface for your AI interactions
• Support for tools/function calling
• Conversation history management
• Persona management
• Image generation capabilities
• Multiple user support

Setting Up big-AGI

1. Clone the big-AGI repository:

   git clone https://github.com/enricoros/big-agi.git
   cd big-agi
   

2. Install dependencies:

   npm install
   

3. Create a .env.local file for configuration:

   cp .env.example .env.local
   

4. Edit the .env.local file to configure your gomcptest server connection:

   # big-AGI configuration
   
   # Your gomcptest OpenAI-compatible server URL
   OPENAI_API_HOST=http://localhost:8080
   
   # This can be any string since the gomcptest server doesn't use API keys
   OPENAI_API_KEY=gomcptest-local-server
   
   # Set this to true to enable the custom server
   OPENAI_API_ENABLE_CUSTOM_PROVIDER=true
   

5. Start big-AGI:

   npm run dev
   

6. Open your browser and navigate to http://localhost:3000 to access the big-AGI interface.

Configuring big-AGI to Use Your Models

The gomcptest OpenAI-compatible server exposes Google Cloud models through an OpenAI-compatible API. In big-AGI, you’ll need to configure the models:

1. Open big-AGI in your browser
2. Click on the Settings icon (gear) in the top right
3. Go to the Models tab
4. Under “OpenAI Models”:
   • Click “Add Models”
   • Add your models by ID (e.g., gemini-1.5-pro, gemini-2.0-flash)
   • Set context length appropriately (8K-32K depending on the model)
   • Set function calling capability to true for models that support it

Enabling Function Calling with Tools

To use the MCP tools through big-AGI’s function calling interface:

1. In big-AGI, click on the Settings icon
2. Go to the Advanced tab
3. Enable “Function Calling” under the “Experimental Features” section
4. In a new chat, click on the “Functions” tab (plugin icon) in the chat interface
5. The available tools from your gomcptest server should be listed

Configuring CORS for big-AGI

If you’re running big-AGI on a different domain or port than your gomcptest server, you’ll need to enable CORS on the server side. Edit the OpenAI server configuration:

1. Create or edit a CORS middleware for the OpenAI server:

   // CORS middleware with specific origin allowance
   func corsMiddleware(next http.Handler) http.Handler {
       return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
           // Allow requests from big-AGI origin
           w.Header().Set("Access-Control-Allow-Origin", "http://localhost:3000")
           w.Header().Set("Access-Control-Allow-Methods", "GET, POST, OPTIONS")
           w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization")
   
           if r.Method == "OPTIONS" {
               w.WriteHeader(http.StatusOK)
               return
           }
   
           next.ServeHTTP(w, r)
       })
   }
   

2. Apply this middleware to your server routes

Troubleshooting Common Issues

Model Not Found

If big-AGI reports that models cannot be found:

1. Verify your gomcptest server is running and accessible
2. Check the server logs to ensure models are properly registered
3. Make sure the model IDs in big-AGI match exactly the ones provided by your gomcptest server

Function Calling Not Working

If tools aren’t working properly:

1. Ensure the tools are properly registered in your gomcptest server
2. Check that function calling is enabled in big-AGI settings
3. Verify the model you’re using supports function calling

Connection Issues

If big-AGI can’t connect to your server:

1. Verify the OPENAI_API_HOST value in your .env.local file
2. Check for CORS issues in your browser’s developer console
3. Ensure your server is running and accessible from the browser

Production Deployment

For production use, consider:

1. Securing your API:

   • Add proper authentication to your gomcptest OpenAI server
   • Update the OPENAI_API_KEY in big-AGI accordingly

2. Deploying big-AGI:

   • Follow the big-AGI deployment guide
   • Configure the environment variables to point to your production gomcptest server

3. Setting up HTTPS:

   • For production, both big-AGI and your gomcptest server should use HTTPS
   • Consider using a reverse proxy like Nginx with Let’s Encrypt certificates

Example: Basic Chat Interface

Once everything is set up, you can use big-AGI’s interface to interact with your AI models:

1. Start a new chat
2. Select your model from the model dropdown (e.g., gemini-1.5-pro)
3. Enable function calling if you want to use tools
4. Begin chatting with your AI assistant, powered by gomcptest

The big-AGI interface provides a much richer experience than a command-line interface, with features like conversation history, markdown rendering, code highlighting, and more.