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Code-defined skills are Python classes that implement robot behaviors with explicit logic. The AI agent reads your code’s function signature and docstrings to understand what the skill does and how to call it.

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Design Principles

The skill SDK is designed to be pythonic—you should be able to read a skill and immediately understand what it does.

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1. The Agent Reads Your Code

The AI agent understands your skill through its Python signature: 
def execute(self, target: str, speed: float = 0.5):
    """Move toward the target object.

    Args:
        target: Object to approach (e.g., "cup", "person")
        speed: Movement speed in m/s
    """
The agent sees execute(target: str, speed: float = 0.5) and knows exactly how to call your skill. Type hints matter—they’re your API contract with the AI.

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2. One-Line Declarations

Dependencies are declared as class attributes, not boilerplate in __init__: 
class MySkill(Skill):
    # Hardware access - one line
    mobility = Interface(InterfaceType.MOBILITY)

    # Sensor data - one line
    image = RobotState(RobotStateType.LAST_MAIN_CAMERA_IMAGE_B64)
The system automatically injects what you declare. No manual wiring.

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3. Direct Access

Once declared, use your dependencies as normal Python attributes: 
def execute(self):
    if self.image:                    # Latest camera frame, updated at 50Hz
        self.mobility.rotate(0.5)     # Rotate 0.5 radians
No callbacks, no message passing, no ROS complexity. Just Python.

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The Skill Class

Every code-defined skill extends Skill and implements these methods: 
from brain_client.skill_types import Skill, SkillResult

class MySkill(Skill):
    @property
    def name(self):
        return "my_skill"  # Unique identifier

    def guidelines(self):
        """Tell the agent when to use this skill."""
        return "Use when you need to [do something specific]"

    def execute(self, param1: str, param2: float = 1.0):
        """Do the thing. Agent calls this with parsed arguments."""
        # Your logic here
        return "Result message", SkillResult.SUCCESS

    def cancel(self):
        """Stop gracefully when interrupted."""
        return "Cancelled"
MethodPurpose
nameUnique identifier the agent uses to call this skill.
guidelines()Natural language instructions for when and how to use the skill.
execute()The actual behavior. The signature defines the skill parameters.
cancel()Clean shutdown when the user or agent interrupts.

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Skill Results

Return a tuple of (message, status) from execute(): 
from brain_client.skill_types import SkillResult

def execute(self):
    if success:
        return "Task completed", SkillResult.SUCCESS
    elif self._cancelled:
        return "Interrupted by user", SkillResult.CANCELLED
    else:
        return "Something went wrong", SkillResult.FAILURE
StatusMeaning
SUCCESSSkill completed its task.
FAILURESomething went wrong.
CANCELLEDSkill was interrupted via cancel().

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Feedback

Send progress updates during long-running skills. The agent reads feedback in real-time and can act on it—for example, canceling the skill or triggering another one immediately: 
def execute(self):
    for i in range(10):
        self._send_feedback(f"Step {i+1}/10")
        # ... do work ...
    return "Done", SkillResult.SUCCESS

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Next Steps