import base64
import io
import logging
import os
import matplotlib
import matplotlib.pyplot as plt
import uvicorn
from fastmcp import FastMCP
from matplotlib import rcParams
from mcp.types import ImageContent
matplotlib.use("Agg")
rcParams['mathtext.fontset'] = 'cm'
rcParams['font.family'] = 'serif'
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)
mcp = FastMCP(
name="latex_mcp",
instructions=(
"Renders LaTeX math expressions into PNG images. "
"Tools return image/png content directly — display it to the user as an image."
),
)
def _render_expression(latex: str, font_size: int = 18, dpi: int = 200,
bg_color: str = "white", text_color: str = "black",
padding: float = 0.25) -> bytes:
fig = plt.figure(facecolor=bg_color)
fig.set_size_inches(0.01, 0.01)
fig.text(0.5, 0.5, f"${latex}$", fontsize=font_size, color=text_color,
ha="center", va="center", usetex=False)
buf = io.BytesIO()
fig.savefig(buf, format="png", dpi=dpi, bbox_inches="tight",
pad_inches=padding, facecolor=bg_color)
plt.close(fig)
buf.seek(0)
return buf.read()
def _render_steps_image(problem: str, steps: list[str], answer: str,
font_size: int = 15, dpi: int = 200) -> bytes:
n = len(steps) + 1
fig_h = max(2.0, n * 0.85 + 0.8)
fig, axes = plt.subplots(n, 1, figsize=(9, fig_h), facecolor="white")
if n == 1:
axes = [axes]
fig.suptitle(problem, fontsize=font_size - 2, color="#333333", style="italic", y=1.0)
for i, (ax, step) in enumerate(zip(axes[:-1], steps)):
ax.set_facecolor("#f9f9f9" if i % 2 == 0 else "white")
ax.axis("off")
ax.text(0.02, 0.5, f"Step {i+1}:" if len(steps) > 1 else "Work:",
transform=ax.transAxes, fontsize=font_size - 3,
color="#666666", va="center", fontweight="bold")
ax.text(0.18, 0.5, f"${step}$", transform=ax.transAxes,
fontsize=font_size, color="#111111", va="center", usetex=False)
ans_ax = axes[-1]
ans_ax.set_facecolor("#dbeafe")
ans_ax.axis("off")
ans_ax.text(0.02, 0.5, "Answer:", transform=ans_ax.transAxes,
fontsize=font_size - 1, color="#1d4ed8", va="center", fontweight="bold")
ans_ax.text(0.18, 0.5, f"${answer}$", transform=ans_ax.transAxes,
fontsize=font_size + 2, color="#1d4ed8", va="center",
fontweight="bold", usetex=False)
fig.tight_layout()
buf = io.BytesIO()
fig.savefig(buf, format="png", dpi=dpi, bbox_inches="tight",
facecolor="white", pad_inches=0.2)
plt.close(fig)
buf.seek(0)
return buf.read()
def _to_image_content(png_bytes: bytes) -> ImageContent:
return ImageContent(
type="image",
data=base64.b64encode(png_bytes).decode(),
mimeType="image/png",
)
@mcp.tool(
name="render_latex",
annotations={"title": "Render LaTeX to PNG", "readOnlyHint": True,
"destructiveHint": False, "idempotentHint": True, "openWorldHint": False},
)
async def render_latex(
latex: str,
font_size: int = 18,
dpi: int = 200,
bg_color: str = "white",
text_color: str = "black",
padding: float = 0.25,
) -> ImageContent:
"""Render a single LaTeX expression and return it as a PNG image.
Do NOT wrap latex in dollar signs — the server adds them automatically.
Args:
latex: LaTeX expression e.g. 'x^2 + y^2 = z^2'. No $ delimiters.
font_size: Font size in points (default 18).
dpi: Image resolution (default 200).
bg_color: Background — 'white' or 'transparent'.
text_color: Equation color (default 'black').
padding: Padding in inches around the equation (default 0.25).
Returns:
PNG image content (image/png) rendered from the LaTeX expression.
"""
logger.info(f"render_latex: {latex[:80]}")
png = _render_expression(latex, font_size, dpi, bg_color, text_color, padding)
return _to_image_content(png)
@mcp.tool(
name="render_solution",
annotations={"title": "Render Full Math Solution", "readOnlyHint": True,
"destructiveHint": False, "idempotentHint": True, "openWorldHint": False},
)
async def render_solution(
problem_description: str,
steps_latex: list[str],
final_answer_latex: str,
font_size: int = 15,
dpi: int = 200,
) -> ImageContent:
"""Render a complete step-by-step math solution as a PNG image.
PRIMARY tool to call after solving any math problem. Renders each step
and the final answer into one clean image with a blue highlighted answer row.
Do NOT wrap any LaTeX strings in dollar signs.
Args:
problem_description: Plain-English problem e.g. 'Solve for x: 2x + 4 = 10'
steps_latex: LaTeX for each step e.g. ['2x+4=10', '2x=6', 'x=3']
final_answer_latex: LaTeX for the final answer only e.g. 'x = 3'
font_size: Font size in points (default 15).
dpi: Image resolution (default 200).
Returns:
PNG image content (image/png) with the full step-by-step solution rendered.
"""
logger.info(f"render_solution: '{problem_description}' — {len(steps_latex)} steps")
png = _render_steps_image(problem_description, steps_latex, final_answer_latex,
font_size, dpi)
return _to_image_content(png)
def main() -> None:
transport = os.environ.get("MCP_TRANSPORT", "streamable-http")
host = os.environ.get("HOST", "0.0.0.0")
port = int(os.environ.get("PORT", "8000"))
logger.info(f"Starting latex_mcp | transport={transport} | {host}:{port}")
if transport in ("streamable-http", "sse"):
app = mcp.http_app(transport=transport)
uvicorn.run(app, host=host, port=port)
else:
mcp.run(transport="stdio")
if __name__ == "__main__":
main()
