★ 11Download for macOS
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Start in the Mecum app, or connect Claude Code or Codex over MCP. Give the agent a small desktop task and check the result yourself.

Platform macOSEntry Mecum app or MCPRuntime On your Mac

What you need

PrepareCheck
MacmacOS 15 or later. Intel Macs are not validated; Compatibility lists the validated configuration.
ProviderUse Claude Code or Codex, or connect a supported model in Mecum, including Gemini or Ollama. Desktop tool use depends on the model. See Models & MCP for connection requirements.
Desktop accessThe three macOS permissions, asked on the first launch and again under Settings → Computer → This Mac. Review what each one allows before granting it.

Choose how you use Mecum

Mecum runs AI agents in desktop apps on your Mac. Create a worker in the Mecum app, or connect Claude Code or Codex over MCP; the MCP guide also covers other local clients.

In the Mecum app

Create a worker, connect a provider and follow messages and tool activity in one workspace.

Open the workspace guide →With Claude Code

Connect Claude Code to Mecum’s desktop tools over MCP.

Set up the connection →With Codex

Connect Codex to Mecum’s desktop tools over MCP.

Set up the connection →

Install and connect

Mecum app

Download Mecum for macOS and open it. In the app, choose Create Worker, Connect Provider… and Allow Mac Access… in that order.

Claude Code or Codex

  1. Keep Mecum open on the same Mac as the client.
  2. In MCP → MCP Connections…, name the client, select its capabilities and click Add Client.
  3. Turn Enabled on and wait for Ready.
  4. Under Client configuration, copy the Claude Code or Codex command and run it in Terminal.
  5. Start a new client session, so it discovers Mecum’s tools.
  6. Run the read-only first check: permission status, running apps and their windows, without changing anything.

Models & MCP has the full setup, the templates for other local MCP clients and the first-check prompt.

Download

Mecum comes as a DMG from its GitHub release; Compatibility lists the requirements. The MCP steps follow the setup guide checked on October 6, 2026; Models & MCP states its scope.

Run a small task

Open the app and the window you want the agent to use. Use a test document for your first run. Then run a small task:

  1. Name the app and the intended result. Specify the document or window and what should change.
  2. Set a boundary. Say what the agent should leave untouched and where it should stop.
  3. Follow the activity. Read tool results as the worker progresses. A connected model alone does not confirm desktop access.
  4. Check the app. Compare its final state with your request before continuing.
Example request · adapt the app and document to your task
In the open test document, change the heading to “Project notes”.
Leave the body text unchanged. Stop before saving.

Check the result

A reply saying “done” is not enough. Check the action evidence and the current app state.

If you seeDo this
Confirmed changeCompare the observed change with the requested result.
Uncertain effectInspect the window before retrying. Input may already have taken effect.
Unavailable targetOpen or identify the intended window, then request a fresh observation.
Action not admittedCheck permissions, session ownership or the reported window state before continuing.

These are plain-language categories. The tools report found_acted, acted_unverified, acted_noop, ambiguous, honest_miss and refused; Background explains each one, and Workspace explains messages and events.

Compatibility

Mecum is built for macOS 15 or later. The desktop seat has been validated on one configuration so far: macOS 27.0, build 26A5425a, on a MacBook Pro with Apple M4 (Mac16,1). On any other build the app still works and shows Seat: Not Validated under Settings → Computer → This Mac, recording that status with each action. Intel Macs are not validated.

Troubleshooting

Use Workspace for workers, conversations and Stop. Use Models & MCP for connection issues. Use Permissions & data for the macOS grants and where files live.

For the underlying system, read Perception for window-to-text, Memory & Brain for learned app knowledge, Background for the desktop seat and Architecture for the full execution path.

Verified source

Checked against Mecum app source at main 524eb7f on October 1, 2026. UI labels and paths have not yet been checked against the signed release build.