agency-swarm-cn-git/docs/welcome/getting-started/from-scratch.mdx

---
title: "From Scratch"
description: "Quick start guide to building an Agency from scratch."
icon: "code"
---

<Note>
Use this guide when you need to build everything manually. Otherwise, start from the [Starter Template](/welcome/getting-started/starter-template).
</Note>

<Steps>
  <Step title="Set Your OpenAI Key">
    Begin by setting your OpenAI API key in the `.env` file. It will be loaded automatically on agency initialization.

    ```
    OPENAI_API_KEY=sk-...
    ```
  </Step>

  <Step title="Create Project Structure">
    When you run the create-agent-template command, it creates the following folder structure for your agent:

    <Accordion title="Create the folder with the CLI" defaultOpen={false}>
      ```bash
      agency-swarm create-agent-template "Developer"
      ```
    </Accordion>

    **Agent Folder Structure:**

    ```
    /your-agency-path/
    └── agent_name/                   # Directory for the specific agent
        ├── files/                    # Directory for files that will be uploaded to openai
        ├── schemas/                  # Directory for OpenAPI schemas to be converted into tools
        ├── tools/                    # Directory for tools to be imported by default.
        ├── agent_name.py             # The agent definition module
        ├── __init__.py               # Initializes the agent folder as a Python package
        └── instructions.md or .txt   # Instruction document for the agent
    ```

    This structure ensures that each agent has its dedicated space with all necessary files to start working on its specific tasks.

    **Agency Folder Structure:**

    The full structure of the project will look like this:

    ```
    agency_name/
    ├── agent_name/           # Agent folder created with the command above
    ├── another_agent/        # Another agent folder
    ├── agency.py             # Main file where agents are imported and the agency is defined
    ├── agency_manifesto.md   # Shared instructions and guidelines for all agents
    ├── requirements.txt      # File listing all dependencies
    └── ...
    ```
  </Step>

  <Step title="Create Tools">
    You have 2 ways of defining custom tools:

    **my_custom_tool.py:**

    ```python
    from agency_swarm import function_tool

    @function_tool
    def my_custom_tool(example_field: str) -> str:
        """
        A brief description of what the custom tool does.
        The docstring should clearly explain the tool's purpose and functionality.
        It will be used by the agent to determine when to use this tool.

        Args:
            example_field: Description of the example field, explaining its purpose and usage for the Agent.

        Returns:
            Result of the tool's operation as a string.
        """

        # Your custom tool logic goes here
        do_something(example_field)

        # Return the result of the tool's operation as a string
        return "Result of MyCustomTool operation"
    ```

    <Accordion title="Preferred: BaseTool class version" defaultOpen={false}>
      **my_custom_tool_class.py:**

      ```python
      from agency_swarm.tools import BaseTool
      from pydantic import Field

      class MyCustomTool(BaseTool):
          """
          A brief description of what the custom tool does.
          The docstring should clearly explain the tool's purpose and functionality.
          It will be used by the agent to determine when to use this tool.
          """

          # Define the fields with descriptions using Pydantic Field
          example_field: str = Field(
              ..., description="Description of the example field, explaining its purpose and usage for the Agent."
          )

          # Additional Pydantic fields as required
          # ...

          async def run(self):
              """
              The implementation of the run method, where the tool's main functionality is executed.
              This method should utilize the fields defined above to perform the task.
              Doc string is not required for this method and will not be used by your agent.
              """

              # Your custom tool logic goes here
              do_something(self.example_field)

              # Return the result of the tool's operation as a string
              return "Result of MyCustomTool operation"
      ```
    </Accordion>

    BaseTool classes support `async def run(...)`, which is preferred for I/O-bound tools.

    See [Custom Tools](/core-framework/tools/custom-tools/step-by-step-guide) for full patterns.
  </Step>

  <Step title="Define Agent Roles">
    Adjust the parameters and instructions for each agent.

    **developer.py:**

    ```python
    from agency_swarm import Agent, ModelSettings
    from agency_swarm import Reasoning
    from .tools.my_custom_tool import my_custom_tool
    from .tools.my_custom_tool_class import MyCustomTool

    developer = Agent(
        name="Developer",
        description="Responsible for executing tasks.",
        instructions="./instructions.md",
        tools=[my_custom_tool, MyCustomTool],  # Import tools directly
        model="gpt-5.4-mini",
        model_settings=ModelSettings(
            temperature=0.3,
            max_tokens=25000,
            reasoning=Reasoning(effort="medium"),
        ),
    )
    ```

    `model` and `reasoning` are both set explicitly in this configuration.

    <Accordion title="Alternative: load tools/files/schemas from folders" defaultOpen={false}>
      ```python
      from agency_swarm import Agent, ModelSettings
      from agency_swarm import Reasoning

      developer = Agent(
          name="Developer",
          description="Responsible for executing tasks.",
          model="gpt-5.4-mini",
          instructions="./instructions.md",
          tools_folder="./tools",
          files_folder="./files",
          schemas_folder="./schemas",
          model_settings=ModelSettings(
              max_tokens=25000,
              reasoning=Reasoning(effort="medium"),
          ),
      )
      ```
    </Accordion>

    **instructions.md:**

    ```md
    You are a Developer agent responsible for executing tasks.

    # Role
    You are responsible for writing clean, efficient, and reusable code.

    # Process
    1. How to handle incoming requests
    2. When and how to use available tools
    3. How to collaborate with other agents
    ```
  </Step>

  <Step title="Create Agency">
    Import your agents and initialize the Agency class.

    **agency.py:**

    ```python
    from agency_swarm import Agency
    from .developer import developer
    from .ceo import ceo

    agency = Agency(
        ceo,  # Entry point agent as positional argument
        communication_flows=[
            ceo > developer,  # CEO can initiate communication with Developer
        ],
        shared_instructions='./agency_manifesto.md'  # shared instructions for all agents
    )
    ```

    The first positional argument is the entry point agent that users interact with directly. Communication flows are defined separately.

    <Note title="Note on Communication Flows">
      In Agency Swarm, communication flows are directional. For instance, in the example above: `ceo > developer`, the CEO can initiate a chat with the Developer, and the Developer can respond in this chat. However, the Developer cannot initiate a chat with the CEO.
    </Note>

    See [Communication Flows](/core-framework/agencies/communication-flows) for multi-agent setups.
  </Step>

  <Step title="Run Demo">
    There are multiple ways to run the demo. Add one of the following to your `agency.py` file:

    **Backend Version (Async):**

    ```python
    import asyncio

    async def main():
        result = await agency.get_response("Please create a new website for our client.")
        print(result.final_output)

    asyncio.run(main())
    ```

    **Terminal Version:**

    ```python
    agency.tui()
    ```

    The first run downloads the matching terminal UI automatically.

    <Accordion title="Other run modes" defaultOpen={false}>
      **Web Interface:**

      ```python
      agency.copilot_demo()
      ```

      **Backend Version (Sync):**

      ```python
      result = agency.get_response_sync("Please create a new website for our client.")
      print(result.final_output)
      ```
    </Accordion>
  </Step>
</Steps>

## Next Steps
- Learn the core concepts: [Tools Overview](/core-framework/tools/overview), [Agents Overview](/core-framework/agents/overview), and [Agencies Overview](/core-framework/agencies/overview).
- Run your first end-to-end flow with [Running an Agency](/core-framework/agencies/running-agency).
- Deploy your project with [Deployment to Production](/additional-features/deployment-to-production).