# Fantasy
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
> [!NOTE]
> Fantasy is currently a preview. Expect API changes.
```go
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](https://github.com/charmbracelet/fantasy/tree/main/examples).
## Multi-model? Multi-provider?
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).
## Work in Progress
We built Fantasy to power [Crush](https://github.com/charmbracelet/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.
## Whatcha think?
We’d love to hear your thoughts on this project. Need help? We gotchu. You can find us on:
- [Slack](https://charm.land/slack)
- [Discord][discord]
- [Twitter](https://twitter.com/charmcli)
- [The Fediverse](https://mastodon.social/@charmcli)
- [Bluesky](https://bsky.app/profile/charm.land)
[discord]: https://charm.land/discord
---
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