/v1/emphasize is the only ACAAS endpoint that thinks for itself. Instead of
uppercasing every character, a small model reads your text and chooses which
words most deserve emphasis. Chosen words are wrapped in markdown bold
(**word**) and returned alongside the originals.
Because a model is in the loop, behavior is non-deterministic. Two identical
requests may produce different results, and the model may change between
versions. Treat this endpoint as a creative collaborator, not a pure function.
Make a request
The body takes atext field and an optional emphasis_ratio. Authentication
is the standard X-API-Key header.
Tune emphasis_ratio
emphasis_ratio controls roughly what fraction of words the model selects.
Values above 0 and up to 1.0 are accepted. The default is 0.3.
The ratio is a guideline, not a guarantee. The model rounds to whole words and
may pick fewer than requested for very short input.
Response shape
original— the text you sent in.result— the text with emphasized words wrapped in markdown bold.emphasized_words— the exact words the model chose, in order of appearance.model— name and version of the emphasis model. Pin against this if you need to detect upstream changes.experimental— alwaystrue. A reminder that behavior may shift.
When to use it
Reach for/v1/emphasize when:
- You want highlights for human readers — release notes, headings, captions.
- The exact wording matters less than the rhythm of emphasis.
- You can render markdown bold downstream.
- You need byte-stable output across calls.
- You are formatting data for machines, not people.
- Markdown is not part of the rendering pipeline — bold asterisks will appear as literal characters.
Errors
Validation errors return HTTP422 with a detail array. The most common
causes are empty text or an emphasis_ratio outside the allowed range.
422 example
401, 413, and 429 cases, see
Quickstart → Handle errors.
Next steps
Full API reference
Complete request and response schema for
/v1/emphasize.Back to the basics
The deterministic, predictable cousin:
/v1/shout.