Forum Discussion
Clarification on Copilot Conversation Length Limits and Copilot Studio Agents
TLDR;
We need clarification on the undocumented Copilot conversation-length limit: how it is determined, whether the M365 Copilot add-on changes it, and whether the same limit applies to Copilot Studio agents using an M365 Copilot (Basic) license in which case the AI Agent license is usage based, so maybe, because we would be paying for the consumption, the same limit would not apply?
Hi,
One of our clients is evaluating the possibility of building a custom AI agent using Microsoft Copilot/Copilot Studio. However, we have some concerns regarding the lack of clear documentation around conversation length limits.
After a certain point, the Copilot chat unexpectedly returns the following message, without any prior warning:
"Sorry, this conversation has reached its limit. Let’s start a new chat."
We have encountered this multiple times, but we have not been able to find any official Microsoft documentation specifying the maximum conversation length or the conditions under which this limit is reached. We have, however, found multiple reports of similar behavior in community forums, including this discussion:
Currently, our client does not have the Microsoft 365 Copilot add-on. When using Copilot, the interface shows “M365 Copilot (Basic)” in the bottom-left corner.
Before we invest further in this approach, we would like to clarify the following:
- What is the officially supported maximum conversation length for M365 Copilot (Basic)? Is there a documented limit in terms of number of messages, tokens, conversation history, or any other measure? If the limit is dynamic or depends on other factors, could you clarify how it is determined?
- Does the conversation length limit also apply to users who have the Microsoft 365 Copilot add-on? In other words, would purchasing the Copilot add-on change or remove this limitation?
- How does this apply to agents built using Copilot Studio? If the client remains on the M365 Copilot (Basic) license but builds an agent using Copilot Studio, we understand that usage of the agent can be subject to usage-based billing.
In this scenario, would the same conversation-length limitation still apply to conversations with a Copilot Studio agent?
Specifically, we are considering a relatively simple declarative agent, without workflows or complex orchestration. The primary requirement is to connect the agent to our CRM through an MCP connector and allow the agent to maintain a conversation with the user while retrieving information from the CRM.
2 Replies
Hi Harshank,
I work on Copilot Studio architecture for clients in regulated industries, and this question comes up a lot when we're scoping agents.
Short answer: there's no published number. I've looked for one too. A Microsoft moderator confirmed on your Q&A thread that Microsoft doesn't document a fixed conversation limit for M365 Copilot Chat, and that it depends on the service and the context. The "30 turns" you'll see everywhere is from the old Bing Chat days, so I wouldn't plan around it.
On the add-on license, I wouldn't count on it lifting the limit. The license changes what Copilot can ground on. It doesn't change how long one chat can run.
The Copilot Studio part is the one that I think matters the most for your design, and it depends on what kind of agent you build.
A declarative agent runs inside M365 Copilot's own chat and orchestrator. I'd assume it hits the same wall as regular Copilot Chat. Microsoft hasn't spelled that out, but that's how it's built. Being billed by consumption doesn't change it.
A custom agent built in Copilot Studio runs on its own runtime, and those limits are documented. On the new harness, the agent keeps the last 100 messages and drops older ones as the conversation grows. The chat doesn't lock. The catch is that it can forget things from early in a long conversation. See the "Agent runtime limits" page on Learn.
For a CRM agent over MCP, I'd lean toward a custom Copilot Studio agent if your users will have long working sessions. You get documented limits you can actually design around, plus proper ALM and governance, which matters once your client's risk team gets involved. A few other things I'd do either way:
- Write anything important back to the CRM, so a fresh chat doesn't lose anything
- Keep the MCP responses lean, with filters, paging and only the fields you need. Big payloads use up context fast
- Pilot it with some realistically long conversations and note where they break. You'll want that evidence if you need to open a ticket or ask Microsoft for a limit increase
Happy to dig into the declarative vs. custom decision if it helps.
From what I have understood so far, is that the conversation length limit is still applicable even with Copilot Add-on on M365 Copilot Chat. However, weather the limit applies to Copilot Studio Declarative Agent is still not clear, and that is what our primary concern is
