# Models and parameters

> How MCP clients discover current model IDs, defaults, constraints, and cost-driving parameters.

Source: https://advibly.com/docs/reference/models



Model availability changes faster than a static documentation page. Before
setting `model`, read the generation tool's input schema from MCP `tools/list`.
Its enum, description, default, compatible modes, resolutions, durations, and
other limits are authoritative.

<Callout>
  Omit `model` to use Advibly's current default. Pin a model only when the
  workflow depends on a capability or visual character unique to that model.
</Callout>

## Select a model only when necessary [#select-a-model-only-when-necessary]

1. Read the target tool's live schema.
2. Omit `model` for the current default unless the job requires a named
   capability such as edit mode, a specific duration, or a particular output
   resolution.
3. Validate the whole combination—model, mode, duration, aspect ratio,
   resolution, and references—against the same schema.
4. Render a cheap proof before raising quality, resolution, duration, or the
   number of outputs.

Selection is complete when every requested parameter is accepted by one model
without relying on clamping or an undocumented fallback.

## Image generation [#image-generation]

`advibly_generate_image` exposes the current image-model enum. The main
cost-driving parameters are:

| Parameter              | Effect                                                                |
| ---------------------- | --------------------------------------------------------------------- |
| `resolution`           | Higher output dimensions cost more.                                   |
| `quality`              | Model-specific quality tier; upper tiers can cost several times more. |
| `num_images`           | Generates and bills for each requested image.                         |
| `reference_image_urls` | Switches supported models into reference/edit mode.                   |
| `on_brand`             | Attaches brand identity references when true.                         |

Use `medium` quality while exploring and raise it only for a final asset when
the selected model supports that value.

## Video generation [#video-generation]

`advibly_generate_video` exposes each current video model plus the allowed
`mode`, `duration`, `resolution`, and media-reference fields. Video is normally
priced by output duration and capability tier; resolution and model choice can
multiply the result.

Different models support different combinations. Do not copy a resolution or
mode from one model to another without checking the live schema.

When a video setting fails repeatedly, return to the default model and one of
its documented combinations, then reintroduce one override at a time.

## Talking actors and audio [#talking-actors-and-audio]

* `advibly_generate_talking_video` lists its current engines, actors, supported
  resolutions, and duration rules.
* `advibly_generate_voiceover` and `advibly_generate_music` expose their current
  voices, models, and length constraints through their schemas.
* `advibly_list_actors` returns the actor IDs accepted by talking-video calls.

## Fixed and utility operations [#fixed-and-utility-operations]

Operations such as video analysis, stitching, subtitles, and composition
rendering have their own schemas and pricing behavior. Use the tool description
returned by `tools/list`, then check [Credit costs](/reference/credit-costs)
before a large workflow.