Build AI agents with Go. Multi-provider, multi-model, one API.

1. Choose a model and provider
2. Add some tools
3. Compile to native machine code and let it rip

import "charm.land/fantasy" import "charm.land/fantasy/providers/openrouter" // Choose your fave provider. provider, err := openrouter.New(openrouter.WithAPIKey(myHotKey)) if err != nil { fmt.Fprintln(os.Stderr, "Whoops:", err) os.Exit(1) } ctx := context.Background() // Pick your fave model. model, err := provider.LanguageModel(ctx, "moonshotai/kimi-k2") if err != nil { fmt.Fprintln(os.Stderr, "Dang:", err) os.Exit(1) } // Make your own tools. cuteDogTool := fantasy.NewAgentTool( "cute_dog_tool", "Provide up-to-date info on cute dogs.", fetchCuteDogInfoFunc, ) // Equip your agent. agent := fantasy.NewAgent( model, fantasy.WithSystemPrompt("You are a moderately helpful, dog-centric assistant."), fantasy.WithTools(cuteDogTool), ) // Put that agent to work! const prompt = "Find all the cute dogs in Silver Lake, Los Angeles." result, err := agent.Generate(ctx, fantasy.AgentCall{Prompt: prompt}) if err != nil { fmt.Fprintln(os.Stderr, "Oof:", err) os.Exit(1) } fmt.Println(result.Response.Content.Text())

🍔 For the full implementation and more see the examples directory.

Fantasy includes built-in support for MLflow tracking and evaluation. A local MLflow server can be started using Docker Compose.

• Docker and Docker Compose installed and running

Start the MLflow server (runs on port 5000):

task mlflow:start

View server logs:

task mlflow:logs

Stop the server:

task mlflow:stop

Once running, the MLflow UI will be available at http://localhost:5000.

The MLflow server uses PostgreSQL as the backend store and includes persistent volumes for both the database and artifact storage.

Yeah! Fantasy is designed to support a wide variety of providers and models under a single API. While many providers such as Microsoft Azure, Amazon Bedrock, and OpenRouter have dedicated packages in Fantasy, many others work just fine with openaicompat, the generic OpenAI-compatible layer. That said, if you find a provider that’s not compatible and needs special treatment, please let us know in an issue (or open a PR).

We built Fantasy to power Crush, a hot coding agent for glamourously invincible development. Given that, Fantasy does not yet support things like:

• Image models
• Audio models
• PDF uploads
• Provider tools (e.g. web_search)

For things you’d like to see supported, PRs are welcome.

We’d love to hear your thoughts on this project. Need help? We gotchu. You can find us on:

• Slack
• Discord
• Twitter
• The Fediverse
• Bluesky

Part of Charm.

Charm热爱开源 • Charm loves open source