Universal Python code execution MCP server - one tool to rule them all.
Inspired by Cloudflare's Code Mode: LLMs are better at writing code than making tool calls because they've trained on millions of real repositories.
Traditional approach (many tools):
User: "Get weather for Austin and save to file"
LLM: [tool_call: get_weather(location="Austin")]
→ waits for response...
LLM: [tool_call: write_file(path="weather.txt", content=...)]
→ waits for response...
Code Mode approach (one tool):
User: "Get weather for Austin and save to file"
LLM: [run_python]
import requests
weather = requests.get("https://wttr.in/Austin?format=j1").json()
temp = weather['current_condition'][0]['temp_F']
with open("weather.txt", "w") as f:
f.write(f"Austin: {temp}°F")
print(f"Saved! Temperature: {temp}°F")
| Traditional Tools | Code Mode |
|---|---|
| ❌ LLMs struggle with synthetic tool-call format | ✅ LLMs excel at writing real code |
| ❌ Each tool call = round trip to LLM | ✅ Complex workflows in one execution |
| ❌ Managing 20+ extensions | ✅ One universal tool |
| ❌ Token waste passing data between calls | ✅ Efficient data flow in code |
| ❌ Limited to pre-built capabilities | ✅ Anything Python can do |
- ✅ Goose (Block's AI agent)
- ✅ Claude Desktop
- ✅ Cursor
- ✅ VS Code with Copilot
- ✅ Any MCP-compatible agent
Write Python to accomplish any task - HTTP requests, file operations, data processing, web scraping, image manipulation, and more.
Missing a package? Code Mode detects ModuleNotFoundError, installs the package, and retries automatically.
See results in real-time! run_python_stream shows output line-by-line as your code executes. Perfect for long-running tasks, progress bars, and monitoring live operations.
Generated images, logs, or data files? Code Mode automatically detects and displays them in your MCP client! Supports:
- Images: PNG, JPG, GIF, SVG, HEIC, TIFF, etc. (displayed inline)
- Text Files: JSON, logs, source code (Python, JS, TS, Go, Rust, etc.), CSV, YAML, etc. (shown with syntax highlighting)
- Resources: PDFs, archives, videos (MP4, MOV), audio (MP3, WAV), Office docs, databases (available for download)
Just print the file path and Code Mode handles the rest! Works seamlessly with Goose and other MCP clients.
Records both error-based and semantic failures:
- Error Learning: Captures errors (ModuleNotFoundError, SSL errors, etc.) and their solutions
- Semantic Learning: Learns when code runs successfully but doesn't accomplish the objective
Future executions benefit from past learnings. Persists across sessions.
run_with_retry analyzes failures and suggests fixes based on both error patterns and semantic learnings from similar tasks.
Run code in isolated Docker containers for enhanced security.
Adjust timeouts, execution modes, package restrictions, and more.
# Using uv (recommended)
uv tool install mcp-pyrunner
# Using pip
pip install mcp-pyrunnergit clone https://github.com/anaseqal/codemode.git
cd codemode
uv syncIf installed from PyPI:
Edit ~/.config/goose/config.yaml:
extensions:
codemode:
type: stdio
enabled: true
cmd: uvx
args: ["mcp-pyrunner"]If running from source (local development):
extensions:
codemode:
type: stdio
enabled: true
cmd: uv
args: ["run", "--directory", "/path/to/codemode", "mcp-pyrunner"]
# Replace /path/to/codemode with actual path (e.g., ~/codemode)Or use the UI: Extensions → Add Custom Extension → STDIO → Command: uv run --directory /path/to/codemode mcp-pyrunner
Edit ~/Library/Application Support/Claude/claude_desktop_config.json:
If installed from PyPI:
{
"mcpServers": {
"codemode": {
"command": "uvx",
"args": ["mcp-pyrunner"]
}
}
}If running from source:
{
"mcpServers": {
"codemode": {
"command": "uv",
"args": ["run", "--directory", "/path/to/codemode", "mcp-pyrunner"]
}
}
}Add to .cursor/mcp.json:
If installed from PyPI:
{
"mcpServers": {
"codemode": {
"command": "uvx",
"args": ["mcp-pyrunner"]
}
}
}If running from source:
{
"mcpServers": {
"codemode": {
"command": "uv",
"args": ["run", "--directory", "/path/to/codemode", "mcp-pyrunner"]
}
}
}| Tool | Description |
|---|---|
get_system_context |
Get environment info (OS, Python, pip versions, package managers, learnings) |
run_python |
Execute Python code (auto-installs packages, auto-displays files) |
run_python_stream |
Execute with real-time streaming output (auto-displays files) |
run_with_retry |
Execute with intelligent retry, error analysis, and semantic learning suggestions |
add_learning |
Record error-based solutions for future reference |
record_semantic_failure |
NEW! Record when code runs but doesn't accomplish objective |
get_learnings |
View/search past learnings (both error and semantic) |
pip_install |
Pre-install a specific package |
configure |
View/update settings |
User: "Scrape the top 10 posts from Hacker News"
→ run_python:
import requests
from bs4 import BeautifulSoup
resp = requests.get("https://news.ycombinator.com")
soup = BeautifulSoup(resp.text, "html.parser")
for i, item in enumerate(soup.select(".titleline > a")[:10], 1):
print(f"{i}. {item.text}")
print(f" {item['href']}\n")
User: "Analyze sales.csv and show monthly totals"
→ run_python:
import pandas as pd
df = pd.read_csv("sales.csv")
df["date"] = pd.to_datetime(df["date"])
monthly = df.groupby(df["date"].dt.to_period("M"))["amount"].sum()
print("Monthly Sales:")
for period, total in monthly.items():
print(f" {period}: ${total:,.2f}")
User: "Get the current Bitcoin price in USD"
→ run_python:
import requests
data = requests.get("https://api.coinbase.com/v2/prices/BTC-USD/spot").json()
price = float(data["data"]["amount"])
print(f"Bitcoin: ${price:,.2f} USD")
User: "Resize all images in ./photos to 800x600"
→ run_python:
from pathlib import Path
from PIL import Image
photos = Path("./photos")
for img_path in photos.glob("*.jpg"):
img = Image.open(img_path)
img.thumbnail((800, 600))
img.save(img_path)
print(f"Resized: {img_path.name}")
User: "Scrape top 20 HN posts with progress updates"
→ run_python_stream:
import requests
from bs4 import BeautifulSoup
import time
print("🔍 Starting to scrape Hacker News...")
resp = requests.get("https://news.ycombinator.com")
soup = BeautifulSoup(resp.text, "html.parser")
stories = soup.select(".titleline > a")[:20]
print(f"📊 Found {len(stories)} stories. Processing...\n")
for i, story in enumerate(stories, 1):
# Show progress in real-time
progress = "█" * i + "░" * (20 - i)
print(f"[{progress}] {i}/20: {story.text}")
time.sleep(0.5) # See each item appear live!
print("\n✅ Scraping complete!")
# Output appears LINE BY LINE as the code runs,
# not all at once at the end!
User: "Take a screenshot of example.com and create a summary report"
→ run_python:
from playwright.sync_api import sync_playwright
import json
with sync_playwright() as p:
browser = p.chromium.launch()
page = browser.new_page()
page.goto("https://example.com")
# Take screenshot
screenshot_path = "/tmp/example_screenshot.png"
page.screenshot(path=screenshot_path)
# Create report
report = {
"url": "https://example.com",
"title": page.title(),
"screenshot": screenshot_path,
"timestamp": "2025-01-26T12:00:00"
}
report_path = "/tmp/report.json"
with open(report_path, "w") as f:
json.dump(report, f, indent=2)
browser.close()
# Print file paths - Code Mode auto-detects and displays them!
print(f"Screenshot saved to: {screenshot_path}")
print(f"Report saved to: {report_path}")
# Result: Your MCP client displays the screenshot IMAGE inline
# and shows the JSON content formatted - no manual handling needed!
View current config:
→ configure()
Update settings:
→ configure(action="set", key="execution_mode", value="docker")
→ configure(action="set", key="default_timeout", value="120")
| Setting | Values | Description |
|---|---|---|
execution_mode |
direct, docker |
How to run code |
default_timeout |
integer | Default timeout (seconds) |
max_retries |
integer | Default retry attempts |
auto_install |
true, false |
Auto-install packages |
docker_image |
string | Docker image for sandbox |
Code Mode learns from two types of failures:
When you solve an error, record it:
→ add_learning(
error_pattern="SSL: CERTIFICATE_VERIFY_FAILED",
solution="Use verify=False or install/update certifi",
context="HTTPS requests on systems with cert issues",
tags="ssl,https,certificates"
)
When code runs successfully but doesn't accomplish the objective:
→ record_semantic_failure(
objective="Display image in Goose app",
failed_approach="Used print() to output file path",
successful_approach="Returned base64 encoded image as MCP content object",
context="MCP clients need structured content objects, not just paths",
tags="goose,mcp,display,images"
)
Why semantic learning matters:
- Code executed without errors ≠ objective accomplished
- AI learns from "technically correct but semantically wrong" approaches
- Future attempts at similar objectives benefit from past semantic learnings
→ get_learnings() # View all learnings (error + semantic)
→ get_learnings(search="ssl") # Search learnings
Learnings are distinguished by icons:
- 🔴 Error-based learnings
- 🔵 Semantic learnings
Learnings persist in ~/.mcp-pyrunner/learnings.json and improve future executions.
Code Mode stores data in ~/.mcp-pyrunner/:
~/.mcp-pyrunner/
├── config.json # User configuration
├── learnings.json # Error patterns and solutions
└── execution_log.json # Recent execution history
Direct mode (default):
- Code runs with your user permissions
- Full filesystem and network access
- Fast execution
Docker mode (more secure):
- Code runs in isolated container
- Limited resources (512MB RAM, 1 CPU)
- Network access available
- Slower startup
Enable Docker mode:
→ configure(action="set", key="execution_mode", value="docker")
# Run tests
uv run pytest
# Test with MCP Inspector
uv run mcp dev src/mcp_codemode/server.py
# Open http://localhost:5173Contributions welcome! Areas of interest:
-
Streaming output for long-running code✅ DONE! -
Automatic file display (images, text, resources)✅ DONE! -
Enhanced system context (pip version, package managers)✅ DONE! - Vector DB for semantic learning search
- Pyodide/WASM sandboxing option
- Code analysis before execution
- Resource usage tracking
- Multi-file project support
MIT
- Cloudflare's Code Mode for the inspiration
- Model Context Protocol for the standard
- Block's Goose for being an excellent MCP client