Vision tool for live conversations
Use thevision tool when visual context changes as the conversation progresses: a customer demonstrates an equipment problem, a participant presents a document in a meeting, or a user shares a screen while troubleshooting. The client sends periodic snapshots, and the assistant chooses when to inspect a recent frame based on the conversation — for example, when the user asks “what am I holding?” or “can you read this error?”
Frames are buffered as they arrive, so the client can keep the view current without triggering an answer for every snapshot. The assistant retrieves visual context on demand by calling vision.
Setting up this path involves both the assistant and the media source: configure the tool, then have your client or integration capture and send snapshots through the realtime conversation WebSocket, the Voice SDK, or the assistant event stream. The model receives individual image snapshots from the camera or screen share. The following sections cover the tool configuration, frame format, and transport examples.
How buffered frames work
- Your client sends frames with a
conversation.item.createframe whose item has"buffer": trueandinput_imagecontent. Telnyx buffers recent frames for the conversation, in memory only. - Nothing else happens. Buffered frames never start an assistant response and are never added to the conversation history, transcripts, or webhooks.
- The assistant decides when to look. With the vision tool enabled, the assistant chooses when to look and which buffered frames it needs. Frames reach the model only when it looks.
- Stale frames are ignored. Frames that Telnyx received more than
max_frame_age_secsago (10 seconds by default) are not shown to the assistant, so it never describes a frozen or disconnected camera as live.
Model support
Vision works in voice-only and avatar conversations, over the conversation WebSocket or WebRTC. An avatar is optional and does not affect whether the assistant can inspect images. Over the WebSocket, the client captures and sends image frames; over WebRTC, it can also send the camera track. The vision tool requires image support from either the assistant’s base model or its enabled delegation model. A speech-to-speech (S2S) assistant can use a vision-capable delegation model even when its speaking model does not support image input. For Telnyx-managed delegation, setdelegation_settings.enabled to true, delegation_settings.mode to "telnyx", and delegation_settings.model to an available model that supports image input. Keep the vision tool attached to the assistant. The delegation model inspects buffered frames and returns its result to the speaking model. See Delegation for backend configuration.
Selecting a vision-capable model in disabled delegation settings does not enable vision. Client delegation (mode: "client") is handled by the connected application; it does not run the configured Telnyx delegation model.
Enable the vision tool
To try vision with an avatar, start with the Avatar with vision template in the Portal. It configures an avatar, the Vision tool, and a model that supports image input. Enable your camera when testing the assistant in the Portal, then ask about something you are showing. For your own integration, capture and send image frames using one of the transports below. Add avision tool to the assistant. Every setting is optional:
{ "type": "vision" } on its own is valid. An assistant can have at most one vision tool. You can also add it in the Portal under Tools → Add Tool → Vision (BETA).
What the model sees
The tool you configure above becomes a single function,vision, that the model can call. It takes two optional arguments:
When a look finds a fresh frame, the image is shown to the model for the rest of that response. Otherwise the model is told that no recent frame is available or, for a tag it has no frames for, which tags are available.
The function name, its description, and its arguments are fixed; only
max_frame_age_secs is configurable. To steer when and how the model looks, use the assistant’s instructions, and refer to the tool and its arguments by these names. For example:
list first.
Send frames
A buffered item is a usermessage with "buffer": true and one or more input_image parts:
If any part is invalid — for example a text part, an unsupported image type, an
http URL, a malformed captured_at, or an invalid tag — the whole item is rejected and nothing is buffered.
The 1 MiB WebSocket limit applies to the entire serialized message, including base64 image data and JSON overhead. A message that exceeds this limit is rejected before buffered-item validation. The realtime socket reports frame_too_large; the assistant event-stream socket returns an error and closes the connection.
Tag frames
Tags are free-form labels your client chooses; Telnyx does not interpret them. The assistant can list the tags it has frames for and look at the frames with a given tag. A common use is telling visual sources apart, for example a participant’s camera and their screen share in a meeting:- Recent frames are buffered per tag, so a tag that receives frames often does not crowd out one that receives them rarely.
- The assistant picks a tag from the list when it needs one (“what is on Oliver’s screen?”). Tag lookups ignore case, spaces, and punctuation.
- Without a tag request, the assistant looks at the most recent frame of any tag. Frames sent without
tagsare grouped together under the reserved nameuntagged, so clients that do not tag frames need no changes. - Choose descriptive tags: the assistant sees them as written.
- Freshness applies per frame. Keep sending frames for content that does not change (such as a static screen share), or the assistant treats it as no longer available after
max_frame_age_secs.
vision tool lists and looks up tags (see What the model sees).
WebRTC (Voice SDK)
Send frames over the active call withsendAIConversationMessage. The SDK forwards the item as-is; in TypeScript its published AIConversationOutboundItem type does not list buffered image items yet, so cast the item until it does:
Realtime WebSocket
On a realtime conversation socket, send theconversation.item.create frame shown above after session.created. For messages within the size limit, an invalid buffered item is answered with an invalid_frame error; the socket stays open.
Assistant event stream
On the customer-configured conversation event stream socket, send the sameconversation.item.create frame. An invalid buffered item is answered with an error frame. Messages exceeding the 1 MiB transport limit also close the connection.