Text messages

Agent Studio can connect multiple named Twilio SMS numbers to a workspace. Each number has its own credentials and label-scoped set of agents, similar to having multiple Slack apps for different teams. A person texts a number, TAS routes the request to one of its connected agents, launches the current stable version, and Twilio sends the result back to the originating phone. Each workspace member links their own phone once, so runs on every workspace number act as that member and use their connections.

SMS opt-in (call to action)

Text-message channels provide request-initiated customer care. Agent Studio does not send marketing texts or start unsolicited conversations.

How members opt in

1. Sign in to your organization’s Agent Studio workspace.
2. Open Build → Text messages and choose Link this phone.
3. Review the SMS consent disclosure shown beside the linking control.
4. Choose an enabled workspace number and send the displayed one-time link command from the mobile phone you want to connect.

Sending the link command proves control of the phone and completes opt-in. It also links the phone to the authenticated workspace member. Linking once lets the member use every enabled number in that workspace; they initiate each conversation by texting the number they want to use.

Consent wording shown to members

By sending the one-time LINK command displayed in your Tembo Agent Studio workspace, you expressly agree to receive customer-care and service-related SMS text messages from Tembo at the mobile number from which you send the command. Messages may include phone-link confirmations, request acknowledgements, agent results, help responses, and service notices.

Message frequency varies based on your activity; each agent request typically generates two messages—one acknowledgement and one result. Msg & data rates may apply. Reply STOP to opt out and HELP for help. Consent is not a condition of purchase. Tembo does not send marketing messages.

Privacy Policy · Terms

An unlinked phone cannot start an agent run. It may receive a single linking, help, or carrier compliance response explaining how to proceed.

Set up a text number

Only a workspace admin can configure text messages. First turn on Settings → General → Text messages → Enable Text Messages and save to show the navigation item for all workspace members.

1. In Twilio, buy or select an SMS-capable phone number.
2. In TAS, open Build → Text messages and choose New text number.
3. Give the number a recognizable name, then enter the Twilio Account SID, Auth Token, and phone number in E.164 form (for example, +14155550123).
4. Enter one or more agent labels as a comma-separated list. Every valid agent carrying at least one of those labels is connected to the number.
5. Copy the webhook URL TAS reveals. In Twilio’s phone-number configuration, set A message comes in to Webhook, paste the URL, choose HTTP POST, and save.
6. Keep Twilio’s standard STOP filtering enabled. For customized STOP, START, and HELP confirmations, add the number to a Twilio Messaging Service and configure Advanced Opt-Out. If the Messaging Service uses the number’s inbound webhook, keep the Agent Studio webhook configured on the number.
7. Each workspace member opens Build → Text messages, chooses an enabled number under Your phone, then texts the displayed one-time link command from their phone. Linking once enables that phone on every text number in the workspace.
8. Send the Twilio number a request. TAS immediately acknowledges a routed request and sends a second message with the agent’s result when the run finishes.

The TAS host must be publicly reachable over HTTPS, and BETTER_AUTH_URL must match that public origin. Twilio signs the exact webhook URL, so a proxy origin that differs from BETTER_AUTH_URL causes requests to be rejected.

Routing a text

Text the agent name followed by its request to route explicitly:

support-triage summarize ticket 42

Agent names match without regard to capitalization. TAS removes the name and passes the rest of the text to that agent. When only one agent is connected to the number, every non-command text routes directly to it.

Otherwise, a text that does not begin with an agent name uses a lightweight classifier to choose the best-fit connected agent. Give each agent a clear description: to make this routing reliable. Natural-language routing requires an Anthropic API key under Settings → LLM Providers; explicit agent-name routing continues to work without that key.

Text agents or list to receive the connected-agent directory. HELP is reserved for SMS help and compliance information and is never routed to an agent. TAS also returns the agent directory instead of starting a run when no agent clearly fits, a request is ambiguous, or natural-language routing is unavailable.

Example message flow

The exact agent names and result content depend on the workspace. A typical conversation looks like this:

Member: link 0123456789ABCDEF
Agent Studio: Phone linked. Send AGENTS to see the available agents.

Member: support-triage summarize ticket 42
Agent Studio: support-triage is working on it. I'll text the result shortly.
Agent Studio: Ticket 42 is waiting on customer confirmation…

Each agent request typically produces two messages: an immediate acknowledgement and the eventual result. Linking, help, validation errors, and carrier compliance commands may produce an additional message. Agent Studio does not send recurring or marketing messages.

STOP, START, and HELP

Twilio handles standard opt-out and opt-in keywords at the provider layer. Agent Studio reserves Twilio’s standard STOP and START keyword sets so they can never be interpreted as agent requests. When Advanced Opt-Out sends an OptOutType webhook, Agent Studio returns no additional message because Twilio has already sent the configured confirmation.

If Twilio has not already handled HELP, Agent Studio replies:

Tembo Agent Studio: Text AGENTS for agent list. Help: tembo.io. Request replies
only. Msg frequency varies. Msg & data rates may apply. Reply STOP to opt out.

Recommended Advanced Opt-Out confirmations identify the sender and preserve the same commands used in the disclosure:

• Opt-out: “Tembo Agent Studio: You have opted out and will receive no more messages from this number. Reply START to resubscribe.”
• Opt-in: “Tembo Agent Studio: You are resubscribed. Reply HELP for help or STOP to opt out.”
• Help: Use the HELP response above.

Identity and connections

The phone that sends a text determines the acting TAS member. Linking starts from an authenticated Agent Studio session and finishes when the member sends a single-use code from that phone. Codes expire after 15 minutes. A phone can identify only one member within a workspace, though the same member can link that phone independently in another workspace.

Every SMS run uses the linked member’s connections. Removing the member from the workspace immediately removes their text access through the membership cascade. Members can unlink their own phone from Build → Text messages. The link is workspace-wide: adding another text number does not require members to link again.

The channel runs the routed agent’s stable version, matching other unattended entry points. Promote a draft before expecting text messages to use it. Changing labels in an agent spec can connect or disconnect that agent from the number without changing the text-message channel.

Security and limits

• Only phones linked by current workspace members can invoke an agent. Unknown numbers cannot start runs. Still treat each text number as an external entry point and give agents narrowly scoped tools.
• TAS verifies every inbound request with Twilio’s X-Twilio-Signature and ignores repeated MessageSid deliveries.
• Standard opt-out, opt-in, and help keywords are reserved before member lookup or agent routing. Twilio remains the source of truth for its recipient block list.
• The Twilio Auth Token is AES-256-GCM encrypted at rest and is never shown again. Leave the token field blank when editing to keep the existing value.
• Each sender can start at most 10 runs per minute on the channel.
• Outbound agent replies are limited to 1,500 characters and receive a truncation marker when longer. Carrier segmentation and Twilio messaging charges still apply.

Disable Accept incoming text messages to pause a number without deleting its settings. Delete a text number to remove its credentials and delivery history without affecting the workspace’s other numbers or member phone links.

Observability

SMS-launched runs appear under Runs with Source = Text and the configured Twilio number. Each launch also records an sms.dispatch audit event. The run’s status remains independent from SMS delivery: a successful agent run can still have a provider delivery error, which the runner records on the delivery row.