MCP Specification Format

FigRecipe provides an MCP (Model Context Protocol) server that allows AI agents to create figures declaratively. This page documents the specification format.

Starting the MCP Server

# Start the MCP server
figrecipe mcp start

# Or using FastMCP directly
fastmcp run figrecipe._mcp.server:mcp

Basic Specification Structure

The declarative specification is a dictionary/YAML with these main sections:

# Figure configuration
figure:
  figsize: [width, height]  # in inches
  dpi: 100
  facecolor: "white"

# Plot data (list of plot specifications)
plots:
  - type: "line"           # Plot type
    x: [1, 2, 3, 4, 5]     # X data
    y: [1, 4, 9, 16, 25]   # Y data
    label: "quadratic"     # Legend label
    color: "blue"          # Line color
    linewidth: 2           # Line width

# Axis labels and title
xlabel: "X Axis"
ylabel: "Y Axis"
title: "My Plot"

# Axis limits (optional)
xlim: [0, 10]
ylim: [0, 30]

# Legend configuration
legend:
  loc: "upper left"
  frameon: true

Plot Types

Line Plot

plots:
  - type: line
    x: [0, 1, 2, 3, 4]
    y: [0, 1, 4, 9, 16]
    color: "blue"
    linewidth: 2
    linestyle: "-"     # "-", "--", "-.", ":"
    marker: "o"        # "o", "s", "^", "v", etc.
    markersize: 5
    label: "data"

Scatter Plot

plots:
  - type: scatter
    x: [1, 2, 3, 4, 5]
    y: [2, 4, 1, 5, 3]
    c: [0.1, 0.3, 0.5, 0.7, 0.9]  # Color values
    cmap: "viridis"               # Colormap
    s: 50                         # Marker size
    alpha: 0.8                    # Transparency
    edgecolors: "black"

Bar Plot

plots:
  - type: bar
    x: ["A", "B", "C", "D"]
    height: [10, 20, 15, 25]
    color: "steelblue"
    edgecolor: "black"
    width: 0.8
    yerr: [1, 2, 1.5, 2.5]  # Error bars
    capsize: 5

# Horizontal bar plot
plots:
  - type: barh
    y: ["A", "B", "C", "D"]
    width: [10, 20, 15, 25]

Histogram

plots:
  - type: hist
    x: [1.2, 1.5, 2.1, 2.3, ...]  # Data values
    bins: 30                       # Number of bins
    color: "steelblue"
    edgecolor: "white"
    alpha: 0.7
    density: false                 # Normalize to density

Box Plot

plots:
  - type: boxplot
    data: [[1,2,3], [4,5,6], [7,8,9]]  # List of datasets
    labels: ["A", "B", "C"]
    notch: false
    vert: true

Violin Plot

plots:
  - type: violinplot
    data: [[1,2,3], [4,5,6], [7,8,9]]
    positions: [1, 2, 3]
    showmeans: true
    showmedians: true

Image/Heatmap

plots:
  - type: imshow
    data: [[1,2,3], [4,5,6], [7,8,9]]  # 2D array
    cmap: "viridis"
    aspect: "auto"
    vmin: 0
    vmax: 10
    interpolation: "nearest"

Contour Plot

plots:
  - type: contourf
    X: [[...], [...]]  # 2D meshgrid X
    Y: [[...], [...]]  # 2D meshgrid Y
    Z: [[...], [...]]  # 2D data values
    levels: 20
    cmap: "coolwarm"

Fill Between

plots:
  - type: fill_between
    x: [0, 1, 2, 3, 4]
    y1: [0, 1, 2, 1, 0]
    y2: 0                 # Can be scalar or array
    alpha: 0.3
    color: "blue"

Error Bar

plots:
  - type: errorbar
    x: [1, 2, 3, 4, 5]
    y: [10, 20, 15, 25, 18]
    yerr: [1, 2, 1.5, 2, 1.8]
    xerr: [0.5, 0.5, 0.5, 0.5, 0.5]
    fmt: "o"
    capsize: 5

CSV Data Input

Instead of inline data, you can reference CSV columns:

plots:
  - type: scatter
    data_file: "experiment_data.csv"
    x_column: "time_seconds"
    y_column: "signal_amplitude"
    c_column: "temperature"    # Optional color column
    cmap: "coolwarm"
    label: "Experiment 1"

Statistical Annotations

Add significance brackets with p-values:

stat_annotations:
  - group1_idx: 0          # Index of first group
    group2_idx: 1          # Index of second group
    p_value: 0.003         # P-value to display
    test: "t-test"         # Test name (optional)
    stars: true            # Show as stars (true) or number (false)

  - group1_idx: 0
    group2_idx: 2
    p_value: 0.05
    text: "ns"             # Custom text instead of p-value

Multi-Panel Figures

Using Axes Array

# Define subplots structure
subplots:
  nrows: 2
  ncols: 2
  figsize: [10, 8]

# Per-axis specifications
axes:
  - position: [0, 0]       # Row, column
    plots:
      - type: line
        x: [0, 1, 2, 3]
        y: [0, 1, 4, 9]
    xlabel: "X"
    ylabel: "Y"
    title: "Panel A"

  - position: [0, 1]
    plots:
      - type: scatter
        x: [1, 2, 3, 4]
        y: [4, 2, 5, 1]
    title: "Panel B"

MCP Tool Reference

plt_plot

Create a figure from specification:

result = plt_plot(
    spec={...},           # Specification dict
    output_path="fig.png",
    dpi=300,
    save_recipe=True      # Also save as .yaml
)

plt_reproduce

Reproduce from saved recipe:

result = plt_reproduce(
    recipe_path="fig.yaml",
    output_path="reproduced.png",
    format="png",
    dpi=300
)

plt_compose

Combine multiple figures:

result = plt_compose(
    sources=["panel_a.png", "panel_b.png"],
    output_path="combined.png",
    layout="horizontal",   # or "vertical", "grid"
    gap_mm=5.0,
    panel_labels=True,
    label_style="uppercase"
)

plt_info

Get recipe information:

info = plt_info(recipe_path="fig.yaml", verbose=True)

plt_validate

Validate reproduction fidelity:

result = plt_validate(
    recipe_path="fig.yaml",
    mse_threshold=100.0
)

plt_crop

Crop whitespace from figure:

result = plt_crop(
    input_path="fig.png",
    output_path="fig_cropped.png",
    margin_mm=1.0
)

plt_extract_data

Extract plotted data from recipe:

data = plt_extract_data(recipe_path="fig.yaml")
# Returns: {call_id: {'x': [...], 'y': [...], ...}}

plt_list_styles

List available style presets:

styles = plt_list_styles()
# Returns: {"presets": ["default", ...], "count": N}

plt_get_plot_types

Get supported plot types:

types = plt_get_plot_types()
# Returns: {"plot_types": [...], "categories": {...}}

Diagram Tools

diagram_create

Create a diagram from YAML specification:

result = diagram_create(
    spec_dict={...},       # Or spec_path="diagram.yaml"
)
# Returns: {"mermaid": "...", "graphviz": "..."}

diagram_render

Render diagram to image:

result = diagram_render(
    spec_path="diagram.yaml",
    output_path="diagram.png",
    format="png",           # png, svg, pdf
    backend="auto",         # mermaid-cli, graphviz, mermaid.ink
    scale=2.0
)

diagram_compile_mermaid

Compile to Mermaid format:

result = diagram_compile_mermaid(
    spec_path="diagram.yaml",
    output_path="diagram.mmd"
)

diagram_compile_graphviz

Compile to Graphviz DOT format:

result = diagram_compile_graphviz(
    spec_path="diagram.yaml",
    output_path="diagram.dot"
)

diagram_list_presets

List available diagram presets:

presets = diagram_list_presets()
# Returns: {"workflow": ..., "decision": ..., "pipeline": ..., "scientific": ...}

diagram_get_backends

Check rendering backend availability:

backends = diagram_get_backends()
# Returns availability and installation instructions

All MCP Tools Summary

Tool	Description
plt_plot	Create figure from declarative spec
plt_reproduce	Reproduce figure from recipe
plt_compose	Combine multiple figures
plt_info	Get recipe information
plt_validate	Validate reproduction fidelity
plt_crop	Crop whitespace from image
plt_extract_data	Extract plotted data arrays
plt_list_styles	List style presets
plt_get_plot_types	Get supported plot types
diagram_create	Create diagram from spec
diagram_render	Render diagram to image
diagram_compile_mermaid	Compile to Mermaid format
diagram_compile_graphviz	Compile to Graphviz format
diagram_list_presets	List diagram presets
diagram_get_preset	Get preset configuration
diagram_get_backends	Check backend availability
diagram_split	Split large diagram into parts
diagram_get_paper_modes	Get paper layout modes