| name | music-stems |
| description | Run 4-stem separation (vocals/drums/bass/other) on an existing production |
| allowed-tools | mcp__cogmusic__separate_stems mcp__cogmusic__get_production |
| argument-hint | <production-id> |
Music Stems
Splits an already-generated production into vocals/drums/bass/other stems.
When to use
The user wants isolated stems from a track they've already generated (remixing, karaoke tracks, sampling). Needs an existing production id — run music-list first if you don't have one.
Steps
- Call
mcp__cogmusic__separate_stems({ id: "<production-id>" }). This is a real GPU job — it takes real time, similar order of magnitude to generation itself, and shares the same underlying inference service as create_production (see the reliability notes in music-generate's SKILL.md — a transient failure is worth one retry before concluding something's wrong).
- This does not return audio. The result only confirms which stems were produced. Check
has_stems via mcp__cogmusic__get_production afterward, then point the user at the dashboard (music.cognitum.one) to actually listen — per ADR-0001, the current cogmusic MCP tool surface doesn't expose a stem-level audio_url the way the primary production audio has one (only the main track's URL is PAT-authorized today).
- If the user specifically needs the stem bytes delivered back through this session rather than via the dashboard, say so plainly — that's a real gap in the current MCP surface, not something this skill can work around.
