Prompting and keyterms

Two config fields steer the transcript as it is written:

Field	Job	Limit
`stt_prompt`	Describes the situation the audio comes from	6000 characters
`keyterms_prompt`	Lists exact terms to expect	100 terms, 8000 characters total

Both act on the transcription itself, before any LLM pass. They are a different lever from llm_instruction, which reshapes the transcript after it has been written.

Contextual prompting

stt_prompt describes what the audio is about. It gives the decoder situational context, which helps it resolve ambiguous audio toward words that make sense in that setting:

{ "stt_prompt": "A doctor dictating a patient visit note." }

Describe the situation rather than instructing the model. stt_prompt is prepended to the base transcription prompt, which always applies, so you are adding context rather than replacing behaviour.

Instead of	Write
”Transcribe this accurately and fix any errors."	"A doctor dictating a patient visit note."
"Output medical terminology."	"A cardiologist dictating notes after a stress test, referring to medications and dosages.”

The field is also accepted as prompt. Send one or the other; sending both is rejected with 400.

Keyterms prompting

keyterms_prompt lists the exact strings you expect to appear: names, drug names, product SKUs, internal jargon. It biases the decoder toward those spellings.

{ "keyterms_prompt": ["amoxicillin", "lisinopril", "metoprolol"] }

This is the same parameter name as the Streaming and Pre-recorded APIs. The legacy names keyterms and word_boost are also accepted; send only one of the three, or the request is rejected with 400. Keep the list to terms that are genuinely hard to transcribe. Common words do not need boosting and dilute the list.

Using both together

The two fields do different jobs and work well in combination. stt_prompt tells the model what kind of audio this is; keyterms_prompt pins the exact spellings it should expect.

Python SDK
Python
JavaScript
cURL

import assemblyai as aai

aai.settings.api_key = "<YOUR_API_KEY>"

config = aai.DictationConfig(
    stt_prompt="A doctor dictating a patient visit note.",
    keyterms_prompt=["amoxicillin", "lisinopril", "metoprolol"],
)

result = aai.DictationTranscriber().transcribe_live("clip.wav", config)
print(result.text)

import json
import requests

config = {
    "stt_prompt": "A doctor dictating a patient visit note.",
    "keyterms_prompt": ["amoxicillin", "lisinopril", "metoprolol"],
}

with open("clip.wav", "rb") as f:
    audio = f.read()

response = requests.post(
    "https://dictation.assemblyai.com/v1/transcribe/live",
    headers={"Authorization": "<YOUR_API_KEY>"},
    files={
        "config": (None, json.dumps(config), "application/json"),
        "audio": ("clip.wav", audio, "audio/wav"),
    },
    timeout=90,
)
response.raise_for_status()
print(response.json()["text"])

import { readFileSync } from "fs";

const config = {
  stt_prompt: "A doctor dictating a patient visit note.",
  keyterms_prompt: ["amoxicillin", "lisinopril", "metoprolol"],
};

const audio = readFileSync("clip.wav");
const form = new FormData();
form.append(
  "config",
  new Blob([JSON.stringify(config)], { type: "application/json" })
);
form.append("audio", new Blob([audio], { type: "audio/wav" }), "clip.wav");

const response = await fetch(
  "https://dictation.assemblyai.com/v1/transcribe/live",
  { method: "POST", headers: { Authorization: "<YOUR_API_KEY>" }, body: form }
);
console.log((await response.json()).text);

curl -X POST https://dictation.assemblyai.com/v1/transcribe/live \
  -H 'Authorization: <YOUR_API_KEY>' \
  -F 'config={"stt_prompt": "A doctor dictating a patient visit note.", "keyterms_prompt": ["amoxicillin", "lisinopril", "metoprolol"]};type=application/json' \
  -F 'audio=@clip.wav;type=audio/wav'

Add llm_instruction on top when you also want the transcript reshaped. The three fields compose: stt_prompt and keyterms_prompt decide what the transcript says, llm_instruction decides what llm_response looks like. See Transcript rewriting.

Limits

Exceeding a limit is rejected with 400:

Field	Limit
`stt_prompt`	6000 characters
`keyterms_prompt`	100 terms, 8000 characters across all terms

DictationConfig in the Python SDK validates both client-side at the same values, so an over-long prompt raises before the request goes out. It also strips whitespace from each keyterm and drops empty ones.

Transcript rewriting reshapes the transcript after it is written.
Language selection sets the language of the audio.

Getting started

Features

API reference

Advanced

Prompting and keyterms

Contextual prompting

Keyterms prompting

Using both together

Limits

​Contextual prompting

​Keyterms prompting

​Using both together

​Limits

​Related features

Contextual prompting

Keyterms prompting

Using both together

Limits

Related features