Code execution

Run language-specific code securely via Heroku tools.

The built-in code execution tools mirror the MCP templates highlighted in Working with MCP. They let agents run small scripts inside one-off dynos—without maintaining a separate MCP server—using the same execution model as the open-source templates.

Supported runtimes

Tool	Runtime	Matching MCP template
code_exec_ruby	Ruby with Gemfile support	mcp-code-exec-ruby
code_exec_python	Python with pip packages	mcp-code-exec-python
code_exec_go	Go modules	mcp-code-exec-go
code_exec_node	Node.js with npm packages	mcp-code-exec-node

Use the table to decide whether the built-in tool is sufficient or if you need to fork the corresponding template for additional customization.

Usage

Provide the language (python, ruby, node, go) and source code. The tool returns stdout, stderr, and the exit status. Keep executions short—long-running jobs should be promoted to a dedicated dyno or background worker.

Example prompt

Run this Python code that sums numbers 1 through 10.

Best practices

• Validate input before execution to avoid unintended side effects.
• Keep scripts idempotent—agents may retry on errors.
• Log execution metadata (target_app_name, timestamps) for auditing.
• When you need more control, deploy your own MCP server using the templates above.