Umbriel MCP Server

Umbriel is an MCP integration. See and drive a whole Windows machine from Bun — apps, input, screen, OCR, registry, OS — via MCP.

Packages and local setup

The published npm package is umbriel, version 1.14.0. Its declared MCP transport is stdio.

The package declares UMBRIEL_PROFILE: Capability profile: 'readonly' (inspect/read only), 'safe' (read + input + window — default), or 'full' (also os + fs tools).; UMBRIEL_OS: Set to '1' to allow the 'os' tools (launch_app/run_program/open_path, kill_process, manage_process, control_service, set_env, registry_get/registry_list/registry_set) AND the 'fs' tools (read_file/write_file/list_dir/stat_path/make_dir/copy_file/move_file/delete_file) regardless of profile.; UMBRIEL_ALLOW: Comma-separated tool names or categories to additionally allow on top of the profile.; UMBRIEL_DENY: Comma-separated tool names or categories to deny, overriding the profile and UMBRIEL_ALLOW.; UMBRIEL_CURSOR: Set to 'never' to forbid the real-cursor fallback entirely (strictly cursor-free). By default clicks/drags are cursor-free but fall back to the real hardware cursor when no cursor-free path exists.; UMBRIEL_FS_ROOT: Sandbox root directory that the fs-category file tools (read_file/write_file/list_dir/stat_path/make_dir/copy_file/move_file/delete_file) are confined to when fs tools are enabled; open_path's path argument is honored too.; UMBRIEL_TRACE: File path to journal every mutating tool call as JSON Lines (tool, category, masked args, ok, observation); secret-bearing args and values are redacted. Unset = no trace.; UMBRIEL_FFI_TRACE: File path to a flush-before-call diagnostic journal of every COM vcall (slot, this-pointer, arg count). Each line is written and flushed to the OS BEFORE the native call, so after an uncatchable crash the last line names the faulting call. Has per-call overhead; unset = off. For debugging native faults only.; UMBRIEL_AUDIT: Controls the default-on stderr audit of mutating tool calls. 'off' is the explicit opt-out (reported at startup); 'verbose' also audits reads.; UMBRIEL_REDACT: Credential masking (default on). 'off' opts out; a regex value overrides the built-in secret shapes masked in clipboard/env/registry reads and the trace journal..

Before connecting

Check the maintainer’s instructions for account access, authentication and the supported client configuration. Once connected, inspect the tools your client receives and try a small task that matches the server’s stated purpose. The registry description does not include a verified, complete tool list.

Project and source

View the publisher’s registry entry · Project repository. This profile uses version 1.14.0 from the registry. Registration identifies the publisher namespace; it does not establish that this is a first-party integration for every service it connects.

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