FunctionGemma-270M — Mobile Actions

A fine-tune of unsloth/functiongemma-270m-it that turns a natural-language instruction into a single, validated mobile-action tool call. It targets two uses:

• Mobile test automation — drive an Appium / UiAutomator / Espresso / XCUITest layer from plain-English steps.
• Agentic workflows — let an on-device agent pick the next action as a structured, executable call.

At 270M parameters it runs on CPU, a modest GPU, or fully on-device (LiteRT-LM / Google AI Edge).

Repository layout

Output format

The model emits FunctionGemma's call DSL, e.g.:

<start_function_call>call:tap{selector:<escape>login_button<escape>}<end_function_call>

Parse it with:

import re
CALL = re.compile(r"<start_function_call>call:(\w+)\{(.*?)\}<end_function_call>", re.DOTALL)
ARG  = re.compile(r"(\w+):(?:<escape>(.*?)<escape>|([^,}]*))")

def parse(text):
    out = []
    for name, raw in CALL.findall(text):
        args = {k: (e or p).strip() for k, e, p in ARG.findall(raw)}
        out.append({"name": name, "arguments": args})
    return out

Usage

from transformers import AutoModelForCausalLM, AutoTokenizer
import torch

REPO = "ahmadw/functiongemma-270m-mobile"
tok = AutoTokenizer.from_pretrained(REPO, subfolder="merged_16bit")
model = AutoModelForCausalLM.from_pretrained(REPO, subfolder="merged_16bit").eval()

prompt = tok.apply_chat_template(
    [{"role": "user", "content": "Tap the login button."}],
    tools=TOOLS,                 # the schema below
    tokenize=False, add_generation_prompt=True,
).removeprefix("<bos>")

inputs = tok(prompt, return_tensors="pt")
with torch.no_grad():
    out = model.generate(**inputs, max_new_tokens=128, do_sample=False)
print(tok.decode(out[0][inputs["input_ids"].shape[1]:], skip_special_tokens=True))
# -> <start_function_call>call:tap{selector:<escape>login_button<escape>}<end_function_call>

You must pass the tools schema (below) so the chat template declares the available actions.

Reliable tool calls (recommended)

For production, constrain decoding so the model can only emit a syntactically valid call naming one of your tools (prevents hallucinated names). Pair the model with xgrammar — build an EBNF grammar whose function name is restricted to your tool list, pass it as a LogitsProcessor to generate(...), and snap any out-of-schema name to the nearest valid tool as a dependency-free fallback.

Wiring into an automation driver

The model decides what; your driver decides how. Map each tool name to a concrete action:

HANDLERS = {
    "launch_app": lambda d, app_name:       d.activate_app(app_name),
    "tap":        lambda d, selector:       d.find(selector).click(),
    "type_text":  lambda d, selector, text: d.find(selector).send_keys(text),
    "swipe":      lambda d, direction:      d.swipe(direction),
    "wait":       lambda d, duration_ms:    d.sleep(duration_ms / 1000),
    # ... one entry per tool ...
}

Selectors come from the live UI. The model infers a reasonable id (e.g. login_button) from the wording; resolve it against the real accessibility tree, or pass the available element ids in the instruction so the model can pick an exact match.

Supported actions (38 tools)

Full tool schema (copy into TOOLS)

[
  {
    "type": "function",
    "function": {
      "name": "launch_app",
      "description": "Launch a mobile application by its visible name.",
      "parameters": {
        "type": "object",
        "properties": {
          "app_name": {
            "type": "string",
            "description": "Visible name of the app to open."
          }
        },
        "required": [
          "app_name"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "close_app",
      "description": "Close or force stop a running application.",
      "parameters": {
        "type": "object",
        "properties": {
          "app_name": {
            "type": "string",
            "description": "Visible name of the app to close."
          }
        },
        "required": [
          "app_name"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "tap",
      "description": "Tap a single UI element once by its selector. Use tap_coordinates for raw screen pixels.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id or label of the element."
          }
        },
        "required": [
          "selector"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "double_tap",
      "description": "Double tap a UI element.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id or label of the element."
          }
        },
        "required": [
          "selector"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "long_press",
      "description": "Press and hold a UI element.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id or label of the element."
          }
        },
        "required": [
          "selector"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "tap_coordinates",
      "description": "Tap the screen at absolute pixel x/y coordinates, with no element selector.",
      "parameters": {
        "type": "object",
        "properties": {
          "x": {
            "type": "integer",
            "description": "Horizontal pixel coordinate."
          },
          "y": {
            "type": "integer",
            "description": "Vertical pixel coordinate."
          }
        },
        "required": [
          "x",
          "y"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "drag",
      "description": "Drag one element onto another.",
      "parameters": {
        "type": "object",
        "properties": {
          "source": {
            "type": "string",
            "description": "Logical id of the element to drag."
          },
          "target": {
            "type": "string",
            "description": "Logical id of the drop target."
          }
        },
        "required": [
          "source",
          "target"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "swipe",
      "description": "Swipe across the screen in a direction.",
      "parameters": {
        "type": "object",
        "properties": {
          "direction": {
            "type": "string",
            "description": "One of: up, down, left, right."
          }
        },
        "required": [
          "direction"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "pinch",
      "description": "Pinch with two fingers to zoom in or out on an element. Does not rotate the screen.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id of the element to zoom."
          },
          "direction": {
            "type": "string",
            "description": "Zoom direction: in or out."
          }
        },
        "required": [
          "selector",
          "direction"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "scroll_to",
      "description": "Scroll until an element becomes visible.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id of the target element."
          }
        },
        "required": [
          "selector"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "pull_to_refresh",
      "description": "Pull down from the top to refresh the screen.",
      "parameters": {
        "type": "object",
        "properties": {},
        "required": []
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "type_text",
      "description": "Type text into an input field.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id of the input field."
          },
          "text": {
            "type": "string",
            "description": "Text to enter into the field."
          }
        },
        "required": [
          "selector",
          "text"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "clear_text",
      "description": "Clear the contents of an input field.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id of the input field."
          }
        },
        "required": [
          "selector"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "paste_text",
      "description": "Paste the clipboard contents into an input field.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id of the input field."
          }
        },
        "required": [
          "selector"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "copy_text",
      "description": "Copy the text of an element to the clipboard.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id of the element to copy from."
          }
        },
        "required": [
          "selector"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "dismiss_keyboard",
      "description": "Hide the on-screen keyboard.",
      "parameters": {
        "type": "object",
        "properties": {},
        "required": []
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "toggle_switch",
      "description": "Set a toggle or switch to a desired state.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id of the switch."
          },
          "state": {
            "type": "string",
            "description": "Desired state: on or off."
          }
        },
        "required": [
          "selector",
          "state"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "set_checkbox",
      "description": "Check or uncheck a checkbox.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id of the checkbox."
          },
          "state": {
            "type": "string",
            "description": "Desired state: checked or unchecked."
          }
        },
        "required": [
          "selector",
          "state"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "select_option",
      "description": "Select an option from a dropdown or picker.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id of the dropdown."
          },
          "option": {
            "type": "string",
            "description": "Visible option to select."
          }
        },
        "required": [
          "selector",
          "option"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "set_slider",
      "description": "Set a slider to a numeric value.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id of the slider."
          },
          "value": {
            "type": "integer",
            "description": "Target value for the slider."
          }
        },
        "required": [
          "selector",
          "value"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "set_date",
      "description": "Set a date picker to a specific date.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id of the date field."
          },
          "date": {
            "type": "string",
            "description": "Date in YYYY-MM-DD format."
          }
        },
        "required": [
          "selector",
          "date"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "set_time",
      "description": "Set a time picker to a specific time.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id of the time field."
          },
          "time": {
            "type": "string",
            "description": "Time in HH:MM 24-hour format."
          }
        },
        "required": [
          "selector",
          "time"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "navigate_back",
      "description": "Go back one step to the previous screen. Does not return to the home screen.",
      "parameters": {
        "type": "object",
        "properties": {},
        "required": []
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "go_home",
      "description": "Return to the device home screen (launcher). This is not a single back step.",
      "parameters": {
        "type": "object",
        "properties": {},
        "required": []
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "open_app_switcher",
      "description": "Open the recent apps or app switcher.",
      "parameters": {
        "type": "object",
        "properties": {},
        "required": []
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "press_keyboard_key",
      "description": "Press a soft keyboard action key.",
      "parameters": {
        "type": "object",
        "properties": {
          "key": {
            "type": "string",
            "description": "One of: enter, search, done, next, go."
          }
        },
        "required": [
          "key"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "open_notifications",
      "description": "Open the notifications panel.",
      "parameters": {
        "type": "object",
        "properties": {},
        "required": []
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "open_quick_settings",
      "description": "Open the quick toggles or control panel.",
      "parameters": {
        "type": "object",
        "properties": {},
        "required": []
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "rotate_screen",
      "description": "Rotate the screen orientation between portrait and landscape. Does not zoom.",
      "parameters": {
        "type": "object",
        "properties": {
          "orientation": {
            "type": "string",
            "description": "Orientation: portrait or landscape."
          }
        },
        "required": [
          "orientation"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "set_volume",
      "description": "Set the media volume to a level.",
      "parameters": {
        "type": "object",
        "properties": {
          "level": {
            "type": "integer",
            "description": "Volume level from 0 to 100."
          }
        },
        "required": [
          "level"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "wait_for_element",
      "description": "Wait until a specific element appears, up to a timeout. Requires an element selector.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id of the element."
          },
          "timeout_ms": {
            "type": "integer",
            "description": "Maximum wait time in milliseconds."
          }
        },
        "required": [
          "selector",
          "timeout_ms"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "wait",
      "description": "Pause execution for a fixed duration in milliseconds. Does not wait for any element.",
      "parameters": {
        "type": "object",
        "properties": {
          "duration_ms": {
            "type": "integer",
            "description": "Duration to wait in milliseconds."
          }
        },
        "required": [
          "duration_ms"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "assert_element_visible",
      "description": "Assert that an element is visible on screen.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id of the element."
          }
        },
        "required": [
          "selector"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "assert_element_not_visible",
      "description": "Assert that an element is not visible on screen.",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id of the element."
          }
        },
        "required": [
          "selector"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "assert_text_equals",
      "description": "Assert that an element's text exactly equals an expected value (full match).",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id of the element."
          },
          "expected_text": {
            "type": "string",
            "description": "Expected text content."
          }
        },
        "required": [
          "selector",
          "expected_text"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "assert_text_contains",
      "description": "Assert that an element's text contains a substring (partial match).",
      "parameters": {
        "type": "object",
        "properties": {
          "selector": {
            "type": "string",
            "description": "Logical id of the element."
          },
          "text": {
            "type": "string",
            "description": "Substring expected within the element text."
          }
        },
        "required": [
          "selector",
          "text"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "take_screenshot",
      "description": "Capture a screenshot of the current screen.",
      "parameters": {
        "type": "object",
        "properties": {
          "name": {
            "type": "string",
            "description": "File name for the screenshot."
          }
        },
        "required": [
          "name"
        ]
      }
    }
  },
  {
    "type": "function",
    "function": {
      "name": "open_url",
      "description": "Open a URL in the default browser.",
      "parameters": {
        "type": "object",
        "properties": {
          "url": {
            "type": "string",
            "description": "Fully qualified URL to open."
          }
        },
        "required": [
          "url"
        ]
      }
    }
  }
]

Evaluation

Greedy + grammar-constrained decoding, on held-out paraphrase sets the model never saw in training:

Hallucinated tool names: 0. Remaining misses cluster on indirect phrasings with no action keyword (e.g. "make the picture smaller" -> pinch out). Accuracy is highest when the instruction names the action.

Training

• Base: unsloth/functiongemma-270m-it
• Method: 16-bit LoRA (r=16, alpha=16; q/k/v/o + gate/up/down) via Unsloth, on a free Tesla T4
• LR 2e-4, linear schedule, adamw_8bit, 3 epochs, response-only loss masking
• Synthetic instruction -> tool-call data with contrastive confusable pairs and broad phrasing variety

License

Governed by the Gemma Terms of Use. Inherits the base model license.