# Copilot Studio and the 5 Different Agent Builders > Source: > Published: 2026-09-07 07:47:42+00:00 We all know Microsoft has been moving at full speed when it comes to AI and agents, and with pace comes changes (and re-naming 😎), but it also brings duplication and overlap. And thats how we have some how arrived at 5 different agent builders available in M365/Power Platform. Note I havent included Foundry/Azure builders because they are more in proc-code world, and the M365/Power Platform have so much overlap with governance, admin, and infra it made sense to group them. So what are the 5 different agent builders, well they are: Lets take a look at each, and then give a big picture on when to use what This was the first agent builder that was available with the M365 Copilot licesne (or whatever is called now). These agents were really just a manifest file, containing a json object, that would be executed by a central engine. They were stored locally as .agent files, and were most prevelent in SharePoint. When you open Copilot in a SharePoint site you would see a list of agents in that site (they were simply .agent files in Documents/Site Assets/Agents, and were published by simply moving the file to the published sub folder), and you could also create a new agent from that screen. They were limited to just SharePoint knowledge sources, had an upgrate to Copilot Studio button (that was always coming soon). The actual .agent files could do more though, with external websites as knowledge sources and a proposed way to call autonamous agents/flows, but I never saw if that came to fruiation. They were planned as they way to create custom agents for M365 Copilot, with the idea you could spin them up for projects and other focused activities. The agent files could be ran from 3 locations: As of now it looks like they have been deprecated, you can no longer make them in SharePoint, and I haven't see any updates for a while. Though the .agent file still works in Teams and M365 Copilot. Governance is interesting as its just a file, so there is little control you can do through MAC (Microsoft Admin Center), its not impacted by PPAC (Power Platform Admin Center). This is what replace .agent files, they are no longer stored locally (I believe in a Cosmo DB database somewhere). Until recently they were similar to .agent files, with knowledge sources only, but they just got updated to enable skills. Skills are awesome tools that enable: Microsoft also calls these plug-ins, so if you see that name know its the same. To create a Skill/plugin you just need to have a folder with your skill name, a file names Skill.md (which contains your context/prompt/knowledge/etc), and optional script.py file and/or template file (.pptx/.docx/.xlsx/txt/etc).You then zip the folder and you have your plug-in. The model being used its definitely not the best (Im 99% certain its a GPT model, probably Tera), I found it can be a little inconsistent, though that can be fixed with a good instruction. There are also some attachment limits - max 20 files, no zip files. These are fully governed in MAC and Agent 365, I haven't seen how to limit sharing but you can control publishing to M365 Copilot for others to find. This is the hidden agent I found that motivated this blog, I've named it Copilot Studio Light, which has been used before but feels right for me (it could also be called Copilots for Microsoft 365). To get to them you have 2 routes, first in Copilot Studio scroll to the bottom and click on **Copilot for Microsoft 365** (now you know where I got the name from 😏). Here you will see a list of the hidden Copilots. You can also get there by using this link: **[https://copilotstudio.microsoft.com/environments/{{environmentID}}/bots/fp/msft_Microsoft365Copilot/agents](https://copilotstudio.microsoft.com/environments/%7B%7BenvironmentID%7D%7D/bots/fp/msft_Microsoft365Copilot/agents)**, just add in your environmentID. When you click create add/create agent you see the normal looking Agent Builder inputs. But that's just a trick, as once its completed you can now add tools. So in the Copilot Studio light you have full tools, you can call connectors, MCP, and Agent Flows. Its pretty much Copilot Studio but with out Topics. There are a few features like evaluation, sub agents, monitor, activity missing, and you are limited to publishing just with Teams and M365 Copilot. It is fully governed by PPAC, with DLP controlling it, though they do not appear in all reports. It is also consumption based if you don't have a M365 Copilot license, so will need Copilot Studio credits for some users (though not for development). I haven't been able to add them to a solution either, so it doesn't appear to be solution aware. The OG, everyone knows this agent builder, so I wont go into too much detail. It is still possible to turn off all of the AI capabilities and make this a "Classic" agent, purely using the topic workflows. But the mix of deterministic topics and generative answers gives it its real power. Add in the ability to call child agents and run them as autonomous agents (triggered by non-chat interactions like emails) means it has significant advantages over Copilot Studio Light. The pricing is a lot more complex, with costs depending on specific combination of AI events. Topic creation, although LowCode, still requires development time compared to all previous (and the next) builders. Its fully within the Power Platform, so under DLP and managed environment sharing controls. It is also solution aware (in fact it can only be unlike Flows and Apps), meaning it is fully ALM compliant. The Copilot Studio GitHub Harness is the latest and most modern agent builder. It follows other agentic tooling like Claude Code, Codex, and of course GitHub Copilot. This means all of the legacy bot builder design is removed, so no topics, instead it is all about skills. I went into more detail about skills/plug-ins in Agent Builder, so this is the same only more powerful (more skill uploads, accepts zip files, and can run longer more complex sessions). In my experience I have also found generally better results/user experience when compared to other agents: It also has memory (which allows the agent to store key information between chats) and deep WorkIQ integration. WorkIQ is Microsoft's "Intelligence Layer", which means it can quickly pull all of your Microsoft information (emails, teams chats, etc), and can use that "big data" to answer/predict more accurately. The big callout here is costs, unlike in all other builders you are charged while developing. So all tests runs, skill building, etc costs real tokens. I suspect this is because its using GitHub Copilots infra, and they are charging the Power Platform team full price. That also means there is no free access to M365 Copilot license holders, and because the models are better/reason more, I have also seen slightly per interaction costs. Yep this version will cost you more. So with that in mind which agent builder should you use, well I would say nearly all have a particular main use case: **Agent files** - don't use them **Agent Builder** - for projects I think this is ideal, as it can only pull data its great for research and project updates. It can also be used for team/department information, but that really should be a SharePoint site with sharepoint.md/skill files. **Copilot Studio Light** - again for projects, but where the use case is beyond just reading. So if you need to create tickets, update trackers, etc, then the this version maybe right All of the above are in my opinion driven to be more tactical, i.e. they have a specific use case which has a fixed lifespan. The short use time is why you wouldn't invest development time in full Copilot Studio **Copilot Studio** - for now this should be your default choice when builder scaled, business imported agents. Its a great choice for a new UI for different software, and can be an awesome orchestrator for complex workflows. **Copilot Studio GitHub Harness** - this is the future, it delivers the best results and quickest development, but with costs this should be used for high value, business critical solutions. There is a lot of overlap with Copilot Studio, you just have to look at the users (if they M365 Copilot License) and the ROI on each user interaction.