A bidirectional Model Context Protocol (MCP) server for REAPER, enabling AI-assisted music composition, track management, and project organization.

The project consists of two main components:

1. Python MCP Server: Exposes a set of high-level tools via the FastMCP framework.
2. Lua Bridge: A background script running inside REAPER that monitors a file-based IPC channel to execute commands and return project state.

• Copy lua_bridge/reaper_mcp_bridge_v2.lua and lua_bridge/rmid_lib.lua to your REAPER Scripts folder.
• Run reaper_mcp_bridge_v2.lua via the Actions list. It will start a deferred loop monitoring for commands.

• Install dependencies: pip install mcp
• Run the server: python -m reaper_mcp.server (or via your MCP client).

• get_project_info(): Get current BPM, time signature, and cursor position.
• set_tempo(bpm): Update the project BPM.
• set_time_signature(numerator, denominator): Update the time signature.
• set_cursor_position(position, is_beats): Move the edit cursor.

• list_tracks(): List all tracks with indices and FX counts.
• create_track(name): Create a new track.
• delete_track(track_index): Remove a track.
• move_track(track_index, target_index): Reorder tracks.
• set_track_volume(track_index, volume_db): Set track gain.
• set_track_color(track_index, r, g, b): Set track visual color.
• set_track_folder_depth(track_index, depth): Manage folder hierarchies (1=start, 0=normal, -1=end).
• set_track_channels(track_index, num_channels): Set total audio channels (e.g., 4 or 6 for sidechaining).
• set_track_mute(track_index, mute): Cleanly mute or unmute a track by its 1-based index.
• set_track_solo(track_index, solo): Cleanly solo or unsolo a track by its 1-based index.
• list_plugin_manufacturers(): List unique plugin manufacturers installed on the system.
• list_vsts(filter): Search for installed VST plugins.
• add_fx(track_index, fx_name): Add an FX/VST to a track.
• delete_track_fx(track_index, fx_index): Remove an FX.
• list_track_fx_params(track_index, fx_index): List all parameters for a specific FX, including current values.
• set_track_fx_param(track_index, fx_index, param_index, value): Set a parameter value (normalized 0.0 to 1.0).
• get_track_fx_pins(track_index, fx_index): List the input/output pin mappings for an FX.
• set_track_fx_pins(track_index, fx_index, is_output, pin_index, channels): Configure which track channels map to which plugin pins.

• list_track_sends(track_index): View outgoing sends.
• create_track_send(source_index, dest_index, volume_db, src_chan, dst_chan): Create a new send. Use strings like "3/4" for sidechains.
• set_track_send_info(track_index, send_index, ...): Update volume, pan, mute, or channel mapping.
• delete_track_send(track_index, send_index): Remove a send.

• get_time_selection(): Get start/end bounds of loop/time range selection (in seconds and beats).
• list_markers(): List all markers and regions with indices, beats, and names.
• create_marker(name, position, is_beats, is_region, end_position): Add a new marker or region to the timeline.
• get_selected_items(): List all currently selected media items (Audio/MIDI) and their track indices.

• list_media_items(track_index, start_beats, end_beats): List all timeline objects (Audio and MIDI) with their type and position, optionally filtered by range.
• list_midi_items(track_index, start_beats, end_beats): List only MIDI items with detailed note/CC counts, optionally filtered by range.
• move_media_item(track_index, item_index, new_pos_beats): Move any item (Audio or MIDI) to a new position.
• delete_media_item(track_index, item_index): Remove any item from the timeline.
• split_media_item(track_index, item_index, position_beats): Split a media item at a specific beat position.
• set_media_item_length(track_index, item_index, length_beats): Set the length of a specific media item in beats.
• set_media_item_take_offset(track_index, item_index, offset_beats): Set the playback start offset of a media item in beats.
• set_media_item_playrate(track_index, item_index, playrate): Set the playback speed (playrate) of a specific media item.
• set_media_item_pitch(track_index, item_index, pitch): Set the pitch shift of a specific media item in semitones.
• set_media_item_fades(track_index, item_index, fade_in_beats, fade_out_beats): Apply fade-in and fade-out times in beats to a media item.
• insert_automation_point(track_index, envelope_name, position_beats, value): Insert an envelope automation point.
• check_overlapping_items(tolerance_beats): Analyze tracks and report any overlapping audio/MIDI clips.
• get_track_midi(track_index, start_beats, end_beats): Read MIDI data in RMID format, optionally filtered by range.
• get_midi_item(track_index, item_index): Read MIDI data in RMID format for a single specific clip.
• insert_midi_item(track_index, rmid): Add new MIDI data.
• set_midi_item(track_index, item_index, rmid): Replace MIDI content.
• copy_media_item(...): Copy items (supports MIDI pooling for MIDI).
• describe_track(track_index, start_beats, end_beats): Musical analysis of the track content, optionally filtered by range.

The server uses RMID (Reaper Minimalistic Interchange Data) for MIDI exchange. It is a human-readable/LLM-friendly format:

TRACK "Lead"
ITEM 0 4
C4 0 1.0 100
E4 1 1.0 100
G4 2 2.0 100

• REAPER 6.x+
• SWS Extensions (Highly recommended)
• Python 3.10+