generating-audio

Files (3)

• SKILL.md
• eval_cases.json · evals/
• directing-the-read.md · references/

SKILL.md (first lines)

# Audio Generation

Turn a script into spoken audio via the `audio_generate` tool. Two decisions drive quality: **which
voice** reads it, and **how the script is written for the ear**.

**Scope.** Speech — a voice reading written words, delivered as its own audio file. Nothing here makes
non-speech sound, alters audio that already exists, or combines two tracks into one.

Lip-synced dialogue spoken by a character *inside* a video clip belongs to `generating-videos`.

## Workflow

### Step 1: Settle the script

Generate only from the exact words that will be spoken.

- **Supplied** → use them verbatim.
- **Enough to write them** — the product, audience, platform, and length are known → draft the script
  and show it before generating.
- **Not enough** → ask. Never invent a tagline, product claim, or brand name to fill the gap.

**Write to a duration.** Speech runs about two to three words a second, so a fifteen-second read is
thirty to forty-five words. Set the word count before writing, and trim words rather than speeding up
the delivery.

### Step 2: Pick the model

**`eleven-v3` is the default** — the most expressive read, and right for anything heard as a
performance. Reach for another only on a clear signal:

| Reach for another model when the script… | Model |
| --- | --- |
| Is a long, even read — an explainer, documentary narration, an audiobook chapter — where the voice must not drift | `eleven-multilingual-v2` |
| Is high-volume, a throwaway draft, or cost-sensitive, and expressiveness doesn't matter | `eleven-flash-v2.5` |

When the user names a model, use it. Per-request character limits differ sharply between models, and
an over-limit script is rejected rather than truncated — `list_audio_models` carries each ceiling.

### Step 3: Pick the voice

Call `list_voices`, filtered by what the brief demands — `gender`, `accent`, `age`, `use_case`,
`language`, or free-text `search`. Each row carries a `preview_url`. 
**There is no default voice**: every request needs a `voice_id` chosen here, passed as `voice`. 
Display names are not accepted.

- A stated **gender, accent, or age is a hard filter** — apply it, don't trade it away on tone.
  Read the attribute back from the row's own fields; **never infer it from the voice's name**. 
- **Let the user hear the options.** Unless they named a voice, offer two or three candidates with
  their `preview_url`s and let them pick.
- **Choose on tone**: what is the listener doing (half-watching a social clip wants attack and
  momentum; following an explainer wants a voice that stays out of the way), and whose voice is it
  meant to be (a brand narrator should stay neutral enough to reuse; a character should match the
  age and register of the writing).
- **Non-English script** → check the row's `language`, and that the model of Step 2 covers it.
- A `voice_id` the user pastes themselves is taken as given.
- Reuse the chosen `voice_id` for every clip in the job.
- **Nothing matched** → a normal result, not a dead end. Drop the narrowest facet — `use_case`
  first, then `age` — and search again. Only when gender and accent alone come back empty is the
  account genuinely short of voices; then relay the tool's hint verbatim, since the cause and the fix
  differ by provider and by whose key is in use.

### Step 4: Prepare the text

`text` is read out word for word, so write it the way it should sound.

- **Strip anything unspoken** — stage directions, speaker labels, bracketed cues, markdown.
- **Spell out** numbers, dates, currency, acronyms, and URLs as a person would say them.
- **Punctuate for pacing** — commas and full stops become pauses, and are the main lever on rhythm.

Direct the delivery with `stability` and `style` (`references/directing-the-read.md`), never with instructions
written into the text.

### Step 5: Generate

Speech comes **only** from `audio_generate`. If it errors, or no voice fits, say so and stop — never
substitute another text-to-speech tool the host happens to expose. A different engine means a
different voice, no access to the account's voices, and output outside the media directory.

Call `audio_generate` with a `requests` list — one object per clip, up to ten per call.

- Per object: `text` and `voice` (both required — the `voice_id` from Step 3); `model` only when
  Step 2 chose a non-default; `speed`, `stability`, `style`, `similarity_boost`, `format` as needed.
- **Split only where the audio will actually be cut** — per scene, or per section placed separately.
  Objects generate independently, so a continuous read split across two of them seams audibly.
- **Hold one `voice` and `model` across every object**, for the same reason. In a dialogue, one voice
  per character, consistent across that character's lines.
- **Repeat a line to get alternate takes** — different voices when the choice is unclear, or the same
  voice twice at low `stability`. Worth it on one short line, not a whole script.

### Step 6: Return

Share the audio file path(s). When the script was split, label each with the section it covers.

## Edge cases

- **Something other than speech is asked for** (music, sound effects, ambience, re-voicing, dubbing,
  cloning a voice from a sample) → say so plainly rather than substituting something else. In
  particular, do not generate a clip through `generating-videos` to get music or effects out of its
  native audio: that bakes the sound into the picture, so it can never serve as a track the user
  mixes. An already-cloned voice still works by its `voice_id`, and another language works by
  translating the script and generating it fresh.
- **Tracks need mixing or timing** ("the voiceover under the music", "a swoosh on the logo") → deliver
  clean speech and let the user assemble it in their editor.
- **Part of the brief is speech and part isn't** → state the limits in one message up front, then
  deliver the speech. Never generate first and disclose the gaps after.
- **Script over the model's character limit** → split it at a natural break, or switch to a
  higher-ceiling model.
- **`error: "no_voices_available"`** → relay the hint; it distinguishes an empty account from a key
  lacking permission to read voices, and the fixes differ.
- **Part of a batch fails** → keep the takes that worked and resend only the failed lines.
- **The read itself came out wrong** (flat, erratic, mispronounced, stress on the wrong word) →
  `references/directing-the-read.md` diagnoses it symptom by symptom.
- **Safety rejection** → remove the sensitive wording and retry once.
- **Generic failure** → retry once as-is, then report the error.
- **`error: "no_provider_configured"`** → relay the tool's `hint` (the user must set their key).

## Reference

- `references/directing-the-read.md` — tuning the delivery with `stability`, `style`,

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