mcp-local-files: Instructions file for Codex

AGENTS.md

Guidance for Codex and other coding agents working in %USERPROFILE%\mcp-local-files.

Project purpose

This folder contains a minimal local-files MCP server for ChatGPT/Codex. It allows the model to access exactly one local folder through OpenAI Secure MCP Tunnel. The active target folder is read from root-dir.txt by run-mcp.cmd and passed to server.js as ROOT_DIR.

The goal is practical local project assistance: list files, read text files, search text files, write new text files, and safely replace exact text in files.

Important files

server.js       Main MCP stdio server. Keep this simple and dependency-light.
cli.js          npm CLI wrapper, ROOT_DIR helper, and tunnel-client downloader.
package.json    Node package metadata. ESM project, no build step.
run-mcp.cmd     Starts server.js with ROOT_DIR loaded from root-dir.txt.
mcp-here.cmd    Convenience helper: writes the current terminal directory to root-dir.txt.
root-dir.txt    The currently exposed local folder.
README.md       User-facing setup and troubleshooting guide.

Current implementation

server.js uses:

@modelcontextprotocol/sdk
zod
Node fs/promises
Node path
StdioServerTransport

cli.js uses only Node built-ins. It starts server.js, updates root files for --tunnel-here, and downloads OpenAI tunnel-client from official release assets on first use.

cli.js setup opens the OpenAI Tunnels and Runtime API keys pages, asks for tunnel_id and the Runtime API key, creates the tunnel-client profile, and stores the key outside this project folder under the user's private config directory.

Registered tools:

list_files
read_file
search_files
stat_file
copy_file
copy_files
write_file
replace_in_file
read_binary_file_base64
write_base64_file

All tool paths are intended to be relative paths inside ROOT_DIR.

Non-negotiable safety rules

Do not expand access beyond ROOT_DIR without explicit user approval.

Do not change the server to accept arbitrary absolute paths.