Choose how an agent starts

Every agent begins with a trigger. It is the first step on the canvas, and it decides when the agent runs: at 07:00 every weekday, when an email lands in the repairs inbox, when someone asks for the agent in chat, when BigChange reports a new job, or when an engineer rings your Centrus number. When it fires, the trigger hands what it received (the email, the chat request, the job) to the next step, and the rest of the agent works from that.

app.centrus.ai/app/agents/workflow-builder

Agents

Build modular AI workflows with reusable nodes

Daily job summary

1,240 / 10,000 creditsValidateResetDraft saved

Runs5

Settings

Save and Publish4

Weekday mornings

Daily at 07:00 · Mon, Tue, Wed, Thu, Fri

2

Fetch today's jobs

List jobs

Write the summary

GPT-5.6 Terra

Email the summary

1 action enabled

AI builderMap

Ready to publish

3

1. 1The Trigger group in the Nodes panel, with the ten triggers you can choose from.
2. 2The trigger on the canvas. This one is a Schedule Trigger named Weekday mornings, and its summary says when it runs.
3. 3The trigger's settings in the Details panel, shown because the trigger is selected.
4. 4Save and Publish. A trigger only starts runs once the agent is published.
5. 5Runs, where Run now starts the agent by hand while you build and test it.

Waiting is free. No trigger uses credits while it waits, and you are charged when a run happens: 1 automation credit for the run, plus whatever its steps use. Automation credits and usage limits explains the charges.

An agent has exactly one trigger. The same agent cannot run at 07:00 and also start whenever an email arrives. If you need both, build two agents, one for each trigger.

Centrus checks this when you validate or publish. An agent with no trigger, or with two, shows this error and cannot be published until you fix it:

Weekday mornings

Daily at 07:00 · Mon, Tue, Wed, Thu, Fri

Fetch today's jobs

List jobs

Write the summary

GPT-5.6 Terra

Email the summary

1 action enabled

Email received

Outlook · Inbox

1 error

Validation

A workflow must have exactly one trigger node.

!Fix validation errors before publishing.

The message does not point at a node, because the problem is the canvas as a whole. To find the extra trigger, look for a card with no connection dot on its left edge: only triggers are drawn without one. Delete the trigger you do not want, or move it into an agent of its own.

A trigger that is on the canvas but not connected to any step gets a warning instead: The trigger is not connected to anything, so the workflow will not do any work. Connect it to the first step before you publish.

Triggers sit at the top of the Nodes panel, in the Trigger group. There are ten of them:

Fetch today's jobs

List jobs

Write the summary

GPT-5.6 Terra

Email the summary

1 action enabled

Schedule Trigger

Starts the workflow automatically on a recurring schedule you define, such as every hour, daily at a set time, or on specific weekdays.

1. 1Schedule Trigger: runs at set times.
2. 2Chat Trigger: runs when someone asks for the agent in Chat, on the web or WhatsApp.
3. 3Email received: runs when a matching email arrives in Outlook or Gmail.
4. 4The six system alert triggers: BigChange webhook and the five below it for Simpro, Joblogic, Fixflo, Freshdesk and Ostara. Each runs when that system sends an event.
5. 5Incoming voice call: runs when someone rings your Centrus number.

1. 1Open the agent and find the Trigger group at the top of the Nodes panel.
2. 2Drag the trigger onto the canvas, or click it to add it, then move it to the left of your first step.
3. 3Drag from the dot on the trigger's right edge to the dot on the left of the first step. The line sets the order the agent runs in.
4. 4Select the trigger and fill in its settings in the Details panel. Each kind has its own, covered below.

Weekday mornings

Daily at 07:00 · Mon, Tue, Wed, Thu, Fri

No input: a trigger always comes first

Fetch today's jobs

List jobs

Drop the line on the first step

Write the summary

GPT-5.6 Terra

Incoming voice call is the one trigger that brings a step with it. Adding it also adds a Voice AI step, already connected, and selects the Voice AI so you can write what it says to callers.

No setting turns one kind of trigger into another. To swap, add the new trigger, connect it, then delete the old one. In this example, a repairs agent that used to read the repairs inbox now starts from Fixflo, because Northgate Housing reports its repairs there.

Repairs inbox

Outlook · Inbox/Repairs

New Fixflo issue

Reported

1

Read the repair request

GPT-5.6 Terra

Create the job

Create job

1 error

1. 1The new Fixflo webhook, already connected to the first step.
2. 2The bin at the top of the Details panel, which deletes the selected trigger.

1. 1Add the new trigger from the Trigger group and connect it to the agent's first step.
2. 2Select the old trigger and click the bin at the top of the Details panel, or press Delete or Backspace.
3. 3Fill in the new trigger's settings. Nothing carries over: the old trigger's settings and connections are deleted with it.
4. 4Check every step that used the old trigger's data. An Intelligence step that read {{ trigger.json.subject }} from an email gets nothing from a Fixflo event, because the event has different fields.
5. 5Click Validate. While both triggers are on the canvas you will see A workflow must have exactly one trigger node.
6. 6Publish again. Until you do, the live agent keeps starting from the old trigger.

Replacing Email received on a published agent? Switch the agent to Draft first, make the swap, then publish again. Switching to Draft is what disconnects Centrus from the mailbox. If you publish the new trigger without doing this, new emails in the old folder can keep starting runs.

A Schedule Trigger runs the agent at set times. Use it for work that should happen whether or not anything has changed: a job summary for the office at 07:00 each weekday, a list of overdue invoices every Monday, or an hourly check for jobs with no engineer assigned.

Weekday mornings

Daily at 07:00 · Mon, Tue, Wed, Thu, Fri

Fetch today's jobs

List jobs

1. 1Schedule mode: Simple for a repeating interval, Advanced to add a time of day and chosen days, or Dates for a list of exact dates and times.
2. 2Frequency: from every 5 minutes to monthly.
3. 3Run at time, using the 24-hour clock.
4. 4Run on these days, with shortcuts for Weekdays, Weekends and All days.

A schedule costs nothing while it waits, but every run costs at least 1 credit, even when there is nothing to find. Pick the slowest schedule that does the job: every 5 minutes is 288 runs a day. Centrus checks schedules every 5 minutes, so a run starts at the first check after its time and can be a few minutes late.

Full set-up, including dates and monthly runs: Run an agent on a schedule.

Email received runs the agent once for each new email that lands in one Outlook folder or one Gmail label and passes its filters. Use it when work arrives by email: repair requests sent to a shared inbox, supplier invoices, or job sheets that engineers send in.

An email that misses the filters costs nothing and starts no run. To decide on something the filters cannot see, such as whether an email really is a repair request, add an Intelligence step after the trigger. That step costs credits for every email that reaches it.

Centrus starts watching the mailbox when you publish, so emails that arrived earlier are not picked up. The trigger always uses the mailbox connected to it, which means the agent must use Agent-level integration mode. Full set-up: Start an agent when an email arrives.

A Chat Trigger turns the agent into something people can ask for. Anyone with access can type "Chase the overdue invoices for Northgate Housing" on the Chat page or in WhatsApp, and Centrus runs the agent and replies with what it found or did. Use it for jobs people want on request rather than on a timetable.

Chat Trigger

Tool: chase_overdue_invoices

Fetch unpaid invoices

List invoices

1. 1Tool name: the name chat knows the agent by. No two published agents in your organisation can share one.
2. 2Description: tells Centrus when to use the agent, so describe the requests people will make.

A Chat Trigger costs nothing while it waits. Before it works, an admin must turn on Enable Agent Builder chat tools in Settings > Organisation, and only published agents are offered. An agent started from chat can also use Per-user integration mode, so its Outlook and Gmail steps act as the person who asked. Full set-up: Run an agent from chat and WhatsApp.

The six webhook triggers start the agent as soon as another system reports a change, instead of the agent checking for changes on a schedule. Use them when timing matters: a new job in BigChange, a change to a quote in Simpro, a visit update in Joblogic, a repair reported in Fixflo, a new Freshdesk ticket, or a work order assigned in Ostara.

New BigChange job

Job created

Fetch the job

Get job

1. 1Connection: the account the agent uses in that system.
2. 2Event types: tick only the events that should start a run.
3. 3Set this up in BigChange: what to do in BigChange, and the URL to paste there.

Waiting costs nothing, and events you did not tick are ignored at no cost. Each ticked event that arrives starts one run, so tick narrowly: Job modified starts a run every time anyone edits a job.

Ticking events in Centrus is only half the job. Someone also has to tell the other system to send them, and the steps differ for each one (see Who sets each one up, below). To test without waiting for a real event, use Simulate webhook in the trigger's settings. It runs the agent with a sample event for a record you name, and it is a real run: steps that send or change things will do so. Full set-up: Start an agent from a system alert.

Incoming voice call answers when someone rings your organisation's Centrus number, and hands the call to a Voice AI step that talks to the caller. Use it for calls you want handled the same way every time, such as engineers phoning in job updates or tenants reporting a fault out of hours.

The line costs nothing while it waits. A call costs 1 credit for each minute or part of a minute, plus 0.1 credit each time the Voice AI uses a tool. Your organisation can have one published phone line, and an agent that answers calls cannot also make them: the builder says Incoming voice call and Outbound call cannot share one automation. Full set-up: Make outbound calls and answer incoming calls.

Whatever its trigger, you can start an agent yourself. Open Runs in the toolbar, click Run now and choose how to run it. This is how you test while you build, and how you run a one-off job.

What the run starts with depends on the trigger:

• Schedule Trigger: the run starts straight away, as if the time had come.
• Chat Trigger: each parameter gets a sample value: "sample value" for text, 0 for numbers and true for yes or no.
• Email received: the latest email in the folder, if it passes the filters. An empty folder shows This folder has no mail yet., and an email that fails a filter shows a message naming that filter. See Start an agent when an email arrives.
• System alert triggers: Run now has no event to pass on, so use Simulate webhook in the trigger's settings instead.
• Incoming voice call: Run now starts a preview in your browser and does not ring the number.

Run now runs the canvas as last saved, so it works on drafts. You need Edit access, and the agent must have been saved at least once: otherwise you see Save your workflow as a draft first. That lets you connect integrations and test run it. For an agent you only ever start by hand, give it a Schedule Trigger with Frequency set to Manual only (no auto-run). More on testing: Test an agent before it goes live.

Start from what should set the work off. If it is a time of day, use a schedule. If it is something arriving, use the trigger for where it arrives: the mailbox, the system that holds the job, or the phone line. If it is a person asking, use a Chat Trigger.

Schedule Trigger

Starts

At set times, from every 5 minutes to monthly

While waiting

0 credits. Every run costs, even when there is nothing to do.

A job summary each weekday at 07:00

Email received

Starts

When a matching email lands in one Outlook folder or Gmail label

While waiting

0 credits. Emails that miss the filters cost nothing.

Turn repair request emails into jobs

Chat Trigger

Starts

When someone asks for it in Chat, on the web or WhatsApp

While waiting

0 credits. Only published agents are offered.

Chase the overdue invoices for Northgate Housing

System alerts

Starts

When BigChange, Simpro, Joblogic, Fixflo, Freshdesk or Ostara sends an event you ticked

While waiting

0 credits. Events you did not tick cost nothing.

Check every new job has a site contact

Incoming voice call

Starts

When someone rings your Centrus number

While waiting

0 credits. A call costs 1 credit per started minute.

Let engineers phone in job updates

Run now

Starts

When you press it in the Runs window

While waiting

Nothing to wait for. Use it to test, or for one-off jobs.

Try the agent before you publish it

When an event trigger exists for what you are waiting on, prefer it to a fast schedule. A BigChange webhook ticked for Job created runs once for each new job. A schedule that looks for new jobs every 5 minutes runs 288 times a day, whether or not anything has changed.

A trigger only fires once the agent is published. Until then you can build and test with Run now, but nothing outside Centrus starts it. Publishing is also when Centrus does the set-up that needs a live agent: it starts watching the mailbox for Email received, and connects your number for Incoming voice call.

Publishing checks the trigger and stops on anything missing, such as Chat Trigger needs a tool name before it can be published. or BigChange webhook needs at least one event type selected before it can be published.

To pause a live agent, open Settings in the toolbar and change Status to Draft. Centrus asks you to confirm:

While an agent is a draft, its trigger ignores everything that would have started it. Nothing is saved up to run later:

• Schedule Trigger: runs that fall due are skipped. When you publish again, the schedule starts from that moment without catching up.
• Email received: Centrus stops watching the mailbox, and emails that arrive in the meantime are not processed when you publish again.
• System alert triggers: events that arrive are discarded. The other system keeps sending them, so if the agent will stay paused, remove the webhook there too.
• Chat Trigger: chat stops offering the agent.
• Incoming voice call: your number stops answering calls.

Archiving an agent stops its trigger in the same way. More on going live and going back: Publish, pause and restore versions.

Some triggers work as soon as you fill them in. Others need someone to act in another system, and that person is often not the one building the agent. Ask them before you start, so a finished agent is not left waiting.

TriggerWho sets it upWhat they do

Schedule TriggerAnyone who can edit the agentNothing to set up outside Centrus

Email receivedAnyone who can edit the agentConnect Outlook or Gmail on the node. Your Microsoft or Google admin may need to allow mailbox notifications.

Chat TriggerAn organisation admin, onceTurn on Enable Agent Builder chat tools in Settings, Organisation

BigChange webhookA BigChange user with API Key ManagementAdd one webhook on the API key the agent uses, then wait up to 10 minutes

Simpro webhookA Simpro administratorCreate a subscription with the Callback URL and Secret from the node

JobLogic webhookJoblogic supportAsk Joblogic support to add the webhook. It cannot be done in Joblogic itself.

Fixflo webhookA Fixflo administratorCreate a subscription with the Callback URL and Secret from the node

Freshdesk webhookA Freshdesk administratorCreate automation rules that call the Callback URL with the secret header

Ostara webhookAn Ostara portal user, then Ostara SupportAdd a webhook endpoint under API Integration with the URL, username and password from the node. Ostara Support whitelists it.

Incoming voice callAnyone who can edit the agentClaim your organisation's Centrus number on the node. One line per organisation.

Inside Centrus, you need Edit access to the agent to add or change its trigger. Accounts such as the mailbox or the BigChange account are connected on the trigger itself, after you save the agent as a draft. Access levels are covered in Share an agent.