diff --git a/packages/kilo-docs/pages/code-with-ai/agents/custom-models.md b/packages/kilo-docs/pages/code-with-ai/agents/custom-models.md
index db8dc74c64..834ec18ce1 100644
--- a/packages/kilo-docs/pages/code-with-ai/agents/custom-models.md
+++ b/packages/kilo-docs/pages/code-with-ai/agents/custom-models.md
@@ -84,6 +84,7 @@ All fields are optional. When a model ID matches one already in the built-in cat
 | `reasoning`   | `boolean` | Whether the model supports extended thinking                                  |
 | `temperature` | `boolean` | Whether the model supports the temperature parameter                          |
 | `attachment`  | `boolean` | Whether the model supports file attachments                                   |
+| `modalities`  | `object`  | Optional. Supported input and output types: `{ input, output }`               |
 | `limit`       | `object`  | Token limits: `{ context, output, input? }`                                   |
 | `cost`        | `object`  | Pricing per million tokens: `{ input, output, cache_read?, cache_write? }`    |
 | `options`     | `object`  | Arbitrary provider-specific model options                                     |
@@ -91,6 +92,26 @@ All fields are optional. When a model ID matches one already in the built-in cat
 | `provider`    | `object`  | Override `{ npm?, api? }` — the AI SDK package or base API URL for this model |
 | `variants`    | `object`  | Named variant configurations (e.g., different reasoning efforts)              |
 
+### Modalities (modalities)
+
+The `modalities` object declares which content types the model can receive and produce. It is optional — omit it to use defaults from the catalog or fallback to text-only. When `modalities` is provided, both `input` and `output` arrays are required. Each array can include `text`, `image`, `audio`, `video`, or `pdf`.
+
+| Sub-field | Type    | Required         | Description                                      |
+| --------- | ------- | ---------------- | ------------------------------------------------ |
+| `input`   | `array` | Yes (if present) | Content types the model accepts from the user    |
+| `output`  | `array` | Yes (if present) | Content types the model can generate in response |
+
+For a standard text model that can also inspect images, use:
+
+```jsonc
+"modalities": {
+  "input": ["text", "image"],
+  "output": ["text"]
+}
+```
+
+If `modalities` is omitted and the model ID matches a models.dev catalog entry for that provider, Kilo uses the catalog's modalities. For completely custom models with no catalog match, Kilo defaults to text input and text output only. Set `attachment: true` alongside image, audio, video, or PDF input modalities when the provider supports sending those files as attachments.
+
 ### Token Limits (limit)
 
 The `limit` object controls how Kilo manages the model's context window and output length. These values are specified in **tokens**.