/music-generation

name: music-generation
description: Generate music using ElevenLabs Music through Letta. Use when creating instrumental tracks, songs with lyrics, background music, jingles, theme songs, or any AI-generated music composition. Supports prompt-based generation and composition plans for section-by-section control.
license: MIT

ElevenLabs Music Generation (via Letta)

Generate music from text prompts: instrumental tracks, songs with lyrics, and fine-grained control via composition plans. Examples use `music_v2_5`, the most advanced ElevenLabs music model and the endpoint's default.

This skill is adapted from ElevenLabs' `music` skill ([elevenlabs/skills](https://github.com/elevenlabs/skills), MIT; see `LICENSE`). Instead of calling ElevenLabs with your own key, you call Letta's hosted endpoint `POST /v1/audio/music` (or `POST /v1/audio/music/stream`). It forwards the request to ElevenLabs with Letta's key and charges the organization's Letta credits, so you do not need an ElevenLabs API key. The request and response are the same as ElevenLabs "Compose music": a JSON body with the same field names, `output_format` as a query parameter, and the audio file as the response body.

Quick Start

base_url="${LETTA_BASE_URL%/}"

curl -sS -X POST "$base_url/v1/audio/music/stream?output_format=mp3_48000_192" \
  -H "Authorization: Bearer $LETTA_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"prompt":"A chill lo-fi hip hop beat with jazzy piano chords","music_length_ms":30000,"model_id":"music_v2_5"}' \
  --output output.mp3 \
  --write-out '%{http_code} %{content_type}\n'

A `200` with an `audio/...` content type means `output.mp3` is the song. Any other status means `output.mp3` holds a JSON error with a `message` instead; read it (see "Error Handling") and do not share the file.

Use the runtime-provided `LETTA_BASE_URL` and `LETTA_API_KEY` together. Build URLs relative to `${LETTA_BASE_URL%/}` and do not hardcode `https://api.letta.com`. If either variable is missing, the user needs to authenticate with Letta Cloud; do not ask for an ElevenLabs key.

Generation takes a while (roughly 10-30 seconds per minute of music). Prefer `/v1/audio/music/stream`: it sends audio as it is generated, so long songs do not sit on an idle connection. `/v1/audio/music` takes the same request and returns the same file, but may send nothing until the whole song is done, so use it only for short songs. Do not set a short client timeout either way.

Share the saved file the way your current surface supports: attach or upload it to the conversation or channel you are replying in. Keep credit amounts out of replies unless the user asks about cost.

Length

• A song is 3 seconds to 10 minutes (600,000 ms).
• With `prompt`, `music_length_ms` is optional. Leave it out to let the model

choose a length that suits the prompt.

• With `composition_plan`, the length is the sum of the chunk or section

`duration_ms` values; do not also send `music_length_ms`.

• Credits are charged for the length of the audio actually returned, at

ElevenLabs' per-minute price. Before generating, the organization needs enough credits for the longest song the request allows: `music_length_ms`, the plan total, or 10 minutes when a prompt sets no length. Setting `music_length_ms` lowers that requirement.

Models

| Model ID | Best For | |----------|----------| | `music_v2_5` | **Default.** Most advanced: best audio quality and prompt adherence. Chunk-based composition plans. | | `music_v2` | Previous generation. Chunk-based composition plans. | | `music_v1` | Oldest. Section-based composition plans. Use only when explicitly requested. |

Prompting

Describe the music the way a producer would brief a session:

• Genre and mood: "melancholic indie folk", "triumphant orchestral trailer".
• Instrumentation and vocals: "fingerpicked acoustic guitar, soft female vocals".
• Tempo and key when they matter: "90 BPM", "D minor".
• Structure and energy: "starts sparse, builds into a big chorus".
• Lyrics: put them in the prompt for short songs, or use a composition plan

to control which lines land in which section.

• Set `force_instrumental: true` to guarantee no vocals (prompt mode only).

Composition Plans

`music_v2_5` composition plans are an ordered list of `chunks`. Each chunk specifies its own `text` (section label, lyrics, inline cues), `duration_ms`, `positive_styles`, `negative_styles`, and `context_adherence` (`low`, `medium`, or `high`, default `high`). Up to 30 chunks per plan, each 3,000–120,000 ms. Each chunk's `text` supports up to 6,132 characters, with up to 30 lines of 200 characters each. Send the plan instead of `prompt` and `music_length_ms`:

{
  "model_id": "music_v2_5",
  "composition_plan": {
    "chunks": [
      {
        "text": "[Verse]\nWalking down an empty street",
        "duration_ms": 15000,
        "positive_styles": ["pop", "upbeat", "female vocals", "acoustic guitar", "120 BPM", "polished production"],
        "negative_styles": ["dark", "slow"],
        "context_adherence": "high"
      },
      {
        "text": "[Chorus]\nThis is my moment",
        "duration_ms": 15000,
        "positive_styles": ["powerful vocals", "full band"],
        "negative_styles": [],
        "context_adherence": "high"
      }
    ]
  }
}

• Put broader characteristics (genre, instrumentation, vocal style) in `positive_styles`, not in

`text`. The first chunk's styles set the overall tone — include 6–7 styles there.

• Use later chunks' styles for progression: "bass joins in", "building intensity", "drums softening".
• Inline cues in curly braces add moments inside a chunk: `{guitar solo}`, `{vinyl crackle}`.
• Lower `context_adherence` lets a chunk depart from its neighbors, for a bridge or a key change.
• `seed` works with composition plans (not with `prompt`) to make results more repeatable.

For `music_v1`, plans use `positive_global_styles`, `negative_global_styles`, a