Code Runner
Let your coding agent execute snippets and scripts in many languages without leaving the chat thread.
Overview
io.github.formulahendry/code-runner is a Build-phase MCP server that runs multi-language code on demand for agent-driven development loops.
What is this MCP server?
- Runs code across multiple programming languages from MCP tool calls
- Ships as npm package mcp-server-code-runner with stdio MCP transport
- Optional OCI image docker.io/formulahendry/mcp-server-code-runner for containerized installs
- Server schema version 0.1.9 with GitHub source at formulahendry/mcp-server-code-runner
- Fits validate-then-build loops when agents need empirical output, not guessed results
- Published server version 0.1.9 in server metadata
- Two distribution paths: npm mcp-server-code-runner and OCI docker.io/formulahendry/mcp-server-code-runner:0.1.8
- Stdio MCP transport on both packages
What problem does it solve?
Agents often propose code you cannot trust until it actually executes in a real interpreter.
Who is it for?
Indie builders who want quick in-chat execution while prototyping APIs, scripts, and small backend logic.
Skip if: Teams that need hardened multi-tenant sandboxes, long-running jobs, or production-grade CI instead of ad hoc runs.
What do I get? / Deliverables
After you register the server, your agent can run snippets via MCP and base next steps on real stdout, stderr, and exit behavior.
- MCP tools that execute agent-supplied code and return run output
- Faster verify-and-iterate loops during build and ship debugging
- Optional containerized MCP deployment via the OCI package
Recommended MCP Servers
Journey fit
Running and validating code belongs in Build when you are wiring agent workflows and checking behavior quickly. Agent-tooling is the right shelf because the server exists to extend what Claude Code, Cursor, and similar agents can do at runtime.
How it compares
MCP code-execution bridge, not a hosted IDE or full continuous-integration platform.
Common Questions / FAQ
Who is code-runner for?
Solo and indie developers using MCP-capable agents who want fast, language-agnostic snippet execution during build and debug sessions.
When should I use code-runner?
Use it when an agent-generated script, algorithm, or API example needs to be executed and interpreted before you merge or ship changes.
How do I add code-runner to my agent?
Install mcp-server-code-runner from npm or pull the formulahendry Docker image, add a stdio MCP server entry in your agent config, then restart the client so tools appear.