How to install Harness in Codex

To install Harness in Codex, run "codex mcp add harness -- npx -y @autonomous-ai/harness-mcp" in your terminal, then type /mcp in Codex to check it.

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Run the install command

In a terminal, run:

codex mcp add harness -- npx -y @autonomous-ai/harness-mcp

MCP servers run with your permissions. If Harness needs an API key, add it under env in the config. Check its README.

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Does Harness work in Codex?

Yes. Codex supports mcp servers in the codex cli and ide extension, and Harness installs with the steps above.

Harness does not show up in Codex. What now?

Restart Codex fully, check the JSON is valid, and make sure Node.js (for npx) is installed. See common MCP errors and fixes.

Is Harness safe?

It scores 95 of 100. Review the code before you install it, and only give it the access it needs. Grades and details.