How to pass input to connected agent

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Posted on by AZ-01040635-0

Hi all,

I am currently building a multi-agent solution in Copilot Studio, where a main/master agent calls a Connected Agent. I need to pass some input data from the main agent to the connected agent, so that the connected agent can use this data for routing and response generation.

At the moment, I am using the Conversation Start topic inside the connected agent to capture the input. The value passed from the main agent can be retrieved from:

System.Activity.Value

This works correctly when testing inside Copilot Studio. The connected agent is able to receive the input and use it as expected.

However, after publishing the solution to Microsoft Teams, the Conversation Start topic in the connected agent seems to trigger an error. Because of this, the flow cannot continue successfully in Teams.

My current understanding is:

Main agent calls the connected agent.

Input is passed to the connected agent.

Connected agent reads the passed input from System.Activity.Value.

This works in Copilot Studio test mode.

But after publishing to Teams, triggering the connected agent’s Conversation Start topic causes an error.

I would like to ask:

Is using Conversation Start the recommended way to receive input variables in a connected agent?

Why would this work in Copilot Studio but fail after publishing to Teams?

Is there any alternative way to pass input variables to a connected agent, without relying on the Conversation Start topic?

How can I make this scenario work reliably in the Teams channel?

My expected behavior is that the connected agent can receive input from the main agent and use that input directly, instead of depending on the latest user message for routing.

Any guidance or recommended architecture would be greatly appreciated.

Thanks!

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Calling actions from Copilot Studio

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Valantis 6,233 on at

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Hi @AZ-01040635-0,

based on ms docs here is few things to do.

1. Conversation Start is NOT the recommended way to receive input in a connected agent. Microsoft docs confirm the correct pattern is to define explicit input parameters on the connected agent and pass them from the parent via the Redirect node or agent invocation. The input parameters are then accessible as variables inside the connected agent's topics.

2. Works in test but fails in Teams because Teams uses a persistent conversation model where Conversation Start only fires once (the first time the agent is added). In subsequent invocations from the parent agent, Conversation Start doesn't re-trigger. The test panel resets the conversation each time, which is why it appears to work there.

3. The correct alternative: define typed input parameters on the connected agent (go to the connected agent's Overview > Inputs). These parameters are passed explicitly when the parent calls the agent via Redirect. Inside the connected agent, access them as normal topic variables.
4. To make it work reliably in Teams: switch from Conversation Start to the input parameters pattern. The connected agent receives the inputs on every invocation, not just the first.

Ref: https://learn.microsoft.com/en-us/microsoft-copilot-studio/authoring-add-other-agents

Best regards,

Valantis

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11manish 2,782 on at

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For a production-ready multi-agent solution, use explicit input parameters and agent/topic variables to pass data from the Main Agent to the Connected Agent.

Treat Conversation Start as a conversation initialization mechanism rather than a reliable inter-agent communication channel.

If the solution must work consistently in Microsoft Teams, moving the routing logic away from Conversation Start and System.Activity.Value is the most reliable

and supportable approach.

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AZ-01040635-0 26 on at

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I did try use redirect trigger topic to receive input variable, but this did not work actually. The redirect topic did not trigger when I invoke this connected agent from parent agent.

Is there any official documents which talked about how to pass the input variables to connected agent?

Btw this link cannot help: https://microsoft.github.io/mcscatblog/posts/copilot-studio-child-connected-agents-inputs-outputs/

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Valantis 6,233 on at

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Hi @AZ-01040635-0,

The official docs are here for the exact setup: https://learn.microsoft.com/en-us/microsoft-copilot-studio/add-agent-child-agent

The input parameters need to be configured on the connected agent itself, not just in the parent topic. Here's the exact confirmed steps:

1. Go to your connected (child) agent's Agents page in Copilot Studio
2. Select the child agent
3. Scroll to the Inputs section
4. Click Add Input
5. Define a Display name and Description — the description is important because it tells the orchestrator what this input is for so it can fill it correctly
6. Select the Data type
7. Save

Once inputs are defined on the child agent, when you add the agent node in your parent agent's topic, you'll see the inputs available to set values for.

The reason your redirect topic didn't trigger: inputs defined on a child agent are passed at invocation time, not through a topic trigger. You don't need a special redirect topic to receive them the values are directly available as variables inside the child agent's topics once configured correctly.

For the exact variable name in the child agent: after adding the input, the variable name in the child agent follows the camelCase naming pattern we discussed earlier (underscores stripped).

Best regards,

Valantis

✅ If this helped solve your issue, please Accept as Solution so others can find it quickly.

❤️ If it didn’t fully solve it but was still useful, please click “Yes” on “Was this reply helpful?” or leave a Like :).

🏷️ For follow-ups @Valantis.

📝 https://valantisond365.com/

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