Reason — Claude Code MCP server: what it does, how to install
Connects your coding agent to Reason cloud workspaces over a remote HTTP MCP endpoint using OAuth.
claude mcp add --transport http reason https://mcp.reasonmachines.com/mcpWhat Reason does
This MCP server links your development environment to Reason at https://mcp.reasonmachines.com/mcp. It exposes v3 API operations directly to your agent, enabling background task execution, repo inspection, and pull request generation. The package brings no local binaries or hooks.
Authentication relies on browser OAuth rather than hardcoded credentials. New coding runs trigger asynchronously via createSession, returning a session link so you can monitor progress with getSession. File uploads through MCP tools cap at 1 MiB, while server responses stop at 2 MiB. If your task exceeds these sizes, you need the standard REST API.
The project previously ran under the name Ara, whose legacy endpoint now returns HTTP 410. Any old setup pointing to ara.so has broken and needs the new service address.
What it helps with
- Trigger an asynchronous Reason coding session on a repository
- Fix broken CI runs on a pull request without skipping test suites
- Review existing pull requests directly from the client
- Inspect progress and recent outcomes of active Reason sessions
Example prompts for the agent
- /reason-review https://github.com/acme/web/pull/42
- /reason-status
How to install Reason
Platform CLI: remote server
claude mcp add --transport http reason https://mcp.reasonmachines.com/mcpPlatform CLI: remote server
codex mcp add reason --url https://mcp.reasonmachines.com/mcpConfig file
{
"mcpServers": {
"reason": {
"url": "https://mcp.reasonmachines.com/mcp"
}
}
}Config file
{
"servers": {
"reason": {
"type": "http",
"url": "https://mcp.reasonmachines.com/mcp"
}
}
}Platform CLI: remote server
gemini mcp add -t http reason https://mcp.reasonmachines.com/mcpStep by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about Reason
How do I install Reason in Claude Code?
Run claude mcp add --transport http reason https://mcp.reasonmachines.com/mcp. After that, open /mcp in Claude Code and complete the browser authentication prompt.
What does Reason do?
It lets MCP-compatible assistants delegate tasks to Reason cloud agents, which inspect repositories, fix bugs, and create pull requests.
What payload limits apply to the Reason MCP server?
Base64 file uploads cannot exceed 1 MiB, and tool responses have a 2 MiB boundary. Larger transfers must go through the REST interface instead.
