# Agent Prototyping
```elixir
Mix.install([
{:magus, path: "#{__DIR__}/.."},
{:kino, "~> 0.12.0"}
# {:ex_dot, "~> 0.1.0"}
])
Application.put_env(:magus, :model_provider, "openai")
Application.put_env(:magus, :openai_key, System.fetch_env!("LB_OPENAI_KEY"))
```
## New Agent
```elixir
alias LangChain.Message
alias Magus.GraphAgent
alias Magus.AgentChain
write_story_node = fn chain, state ->
prompt = "Write a brief story about \"#{state.topic}\" that features three different characters"
{:ok, content, _last_message} =
chain
|> AgentChain.add_message(Message.new_user!(prompt))
|> AgentChain.run()
%{state | story: content}
end
story_schema = %{
"type" => "object",
"properties" => %{
"summary" => %{
"type" => "string",
"description" => "Brief summary of the story."
},
"characters" => %{
"type" => "array",
"description" => "List of characters in the story",
"items" => %{
"type" => "string"
}
}
}
}
structure_story_node = fn chain, state ->
prompt = """
You are a helpful assistant responsible for summarizing stories and identifying story characters.
The following is a short story about "#{state.topic}":
#{state.story}
"""
{:ok, content, _last_message} =
chain
|> AgentChain.add_message(Message.new_user!(prompt))
|> AgentChain.ask_for_json_response(story_schema)
|> AgentChain.run()
%{state | structured_story: content}
end
agent =
%GraphAgent{
name: "Poff's Great New Agent",
initial_state: %{}
}
|> GraphAgent.add_node(:write_story, write_story_node)
|> GraphAgent.add_node(:structure_story, structure_story_node)
|> GraphAgent.set_entry_point(:write_story)
|> GraphAgent.add_edge(:write_story, :structure_story)
|> GraphAgent.add_edge(:structure_story, :end)
```
<!-- livebook:{"continue_on_error":true} -->
```elixir
# This only works if the ex_dot dependency is available (see the Notebook dependencies section)
agent.graph
|> Graph.Serializers.DOT.serialize()
|> case do
{:ok, dot_graph} -> dot_graph
end
|> Dot.to_svg()
|> Kino.Image.new(:svg)
```
```elixir
import Kino.Shorts
topic = read_text("New story topic: ")
if topic == "" do
Kino.interrupt!(:error, "You must enter a topic")
end
initial_state = %{topic: topic, story: nil, structured_story: nil}
Magus.AgentExecutorLite.run(%{agent | initial_state: initial_state}) |> Kino.Tree.new()
```
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