# Attaching images to prompts (/sessions/attaching-images)



You can attach images to a prompt so the agent can see a screenshot, a design, or an error dialog instead of reading a description of it.

## Limits [#limits]

| Rule               | Value                                  |
| ------------------ | -------------------------------------- |
| Formats            | PNG, JPEG, WebP, GIF                   |
| Images per message | Up to 6                                |
| Size per image     | 10 MiB (the UI rounds this to "10 MB") |

The same limits apply to the web composer, Slack, and forwarded Slack messages.

## From the web composer [#from-the-web-composer]

1. In the new-session composer or a session's prompt composer, click **Attach images**.
2. Pick one or more files. Each accepted image appears as a thumbnail in the preview strip below the composer.
3. Hover a thumbnail and click **Remove** to drop it before sending.
4. Write your prompt and send it. The images are uploaded with the message and stored with the session.

Files that do not pass the checks are skipped with a message next to the composer:

* `<name> is not a supported image` for anything other than PNG, JPEG, WebP, or GIF
* `<name> is too large (images must be under 10 MB)`
* `You can attach up to 6 files per message` once the strip is full

## From Slack [#from-slack]

Attach PNG, JPEG, WebP, or GIF images to:

* a direct message to the bot,
* a channel request that `@mentions` the bot,
* an interactive thread follow-up (in a channel, the follow-up must also `@mention` the bot).

You can include instructions with the images or send images alone. Forwarding (sharing) another Slack message to the bot also carries that message's images, under the same six-image and 10 MiB limits.

If only some images can be read, the rest of the message still reaches the agent and the bot posts a warning in the thread. If an image-only request loses every image, no session is started.

Requirements on the Slack app side:

* the `files:read` bot scope, and a reinstall after the scope was added;
* `channels:history` (public channels) or `groups:history` (private channels), so the bot can recover file details Slack omits from mention events.

See [Slack](/integrations/slack) for the full setup.

## How the agent uses images [#how-the-agent-uses-images]

Images are delivered to the agent as part of the prompt, so it can read text in a screenshot, match a design, or locate the element you are pointing at. A typical use:

```text
This is a screenshot of the checkout page after clicking Pay. Fix the visible error and
reproduce the page in the browser to confirm it is gone.
```

The agent can capture its own screenshots and upload them as session media; they appear in the timeline and under **Media** in the right sidebar, where you can compare them with what you sent. See [Reviewing changes](/sessions/reviewing-changes).

## What is not supported [#what-is-not-supported]

* Non-image files (PDFs, logs, archives). Paste text content into the prompt instead, or commit the file to the repository.
* Remote files hosted outside Slack; only files uploaded to Slack are forwarded.
* Attachments on Slack automation triggers. A Slack Message automation starts on the message text alone; the attachment is not forwarded.

## Troubleshooting [#troubleshooting]

| Symptom                                       | Cause                                                                                                      | Fix                                                                                                                                          |
| --------------------------------------------- | ---------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| The composer rejects the file                 | Unsupported type, over 10 MiB, or the message already has 6 images                                         | Convert to PNG, JPEG, WebP, or GIF; export a smaller image; or send the rest in a follow-up.                                                 |
| A Slack image never reached the agent         | Missing `files:read`, the app was not reinstalled after adding it, or the channel history scope is missing | Add `files:read` (and `channels:history` or `groups:history`), reinstall the app, and resend. Check the warning the bot posts in the thread. |
| A channel follow-up with an image was ignored | Channel follow-ups with images need an `@mention`                                                          | Mention the bot in the same thread and attach the image again.                                                                               |

## Next steps [#next-steps]

* [Writing prompts](/prompting/writing-prompts)
* [Slack](/integrations/slack)
* [Session page](/sessions/session-page)