Custom Tools

Custom Tools

Expose your own MATLAB functions as first-class MCP tools. AI agents can discover and call them directly, with full parameter validation and help text.

How It Works

1. Write your MATLAB function (.m file)
2. Describe it in custom_tools.yaml
3. The server registers it as an MCP tool at startup
4. Agents see it alongside built-in tools

Configuration

Point your config.yaml to the custom tools file:

custom_tools:
  config_file: "./custom_tools.yaml"

YAML Format

tools:
  - name: tool_name                # MCP tool name (what agents call)
    matlab_function: pkg.func      # MATLAB function to call
    description: "What it does"    # Shown to agents
    parameters:
      - name: param_name
        type: string               # string | double | int | logical
        required: true             # or false
        description: "What this parameter does"
      - name: optional_param
        type: double
        default: 1.0               # Default value if not provided
        description: "Optional param with default"
    returns: "Description of return value"

Parameter Types

YAML Type	MATLAB Type	Python Type
string	char	str
double	double	float
int	int64	int
logical	logical	bool

Complete Example

1. MATLAB Function (mylib/analyze_signal.m)

function result = analyze_signal(signal_path, sample_rate, window_size)
    % ANALYZE_SIGNAL  Frequency analysis of a signal file
    %
    %   result = analyze_signal(signal_path, sample_rate, window_size)
    %
    %   Returns struct with: frequencies, magnitudes, snr, peaks

    data = load(signal_path);
    signal = data.signal;

    N = length(signal);
    Y = fft(signal, window_size);
    f = (0:window_size/2-1) * sample_rate / window_size;
    mag = abs(Y(1:window_size/2)) / N;

    [peaks, locs] = findpeaks(mag, 'MinPeakHeight', max(mag)*0.1);

    result.frequencies = f;
    result.magnitudes = mag;
    result.snr = snr(signal);
    result.peaks = struct('frequencies', f(locs), 'amplitudes', peaks);
end

2. Custom Tool Definition (custom_tools.yaml)

tools:
  - name: analyze_signal
    matlab_function: analyze_signal
    description: >
      Analyze a signal file and return frequency components, SNR,
      and peak detection results.
    parameters:
      - name: signal_path
        type: string
        required: true
        description: "Path to the signal data file (.mat)"
      - name: sample_rate
        type: double
        required: true
        description: "Sample rate in Hz"
      - name: window_size
        type: int
        default: 1024
        description: "FFT window size"
    returns: "Struct with fields: frequencies, magnitudes, snr, peaks"

3. Make Sure MATLAB Can Find It

Add the directory containing your .m files to the workspace paths in config.yaml:

workspace:
  default_paths:
    - "/path/to/mylib"

4. Agent Usage

The agent now sees analyze_signal as a tool and can call it:

"Analyze the signal in data/recording.mat at 44100 Hz sample rate"

The server:

1. Validates parameters against the YAML schema
2. Calls analyze_signal('data/recording.mat', 44100, 1024) in MATLAB
3. Returns the result to the agent

Multiple Tools

tools:
  - name: analyze_signal
    matlab_function: mylib.analyze_signal
    description: "Frequency analysis of signal files"
    parameters:
      - name: signal_path
        type: string
        required: true
    returns: "Frequency analysis struct"

  - name: train_model
    matlab_function: ml.train_classifier
    description: "Train a classification model"
    parameters:
      - name: dataset_path
        type: string
        required: true
      - name: model_type
        type: string
        default: "svm"
    returns: "Trained model and accuracy metrics"

  - name: process_image
    matlab_function: imgtools.enhance
    description: "Image enhancement pipeline"
    parameters:
      - name: image_path
        type: string
        required: true
      - name: denoise_strength
        type: double
        default: 0.5
    returns: "Enhanced image saved to temp directory"

Tips

• Function names with packages: Use pkg.func notation to call functions in MATLAB packages (e.g., +mylib/analyze_signal.m → mylib.analyze_signal)
• MEX files: Custom tools work with .mex files too — just reference the function name without the extension
• Error handling: If the MATLAB function throws an error, the MCP server returns a structured error response to the agent
• Testing: Test your functions in MATLAB first before exposing them as tools