Copilot Studio new experience not invoking Business Central MCP tools

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Posted on by CU30060856-1

Hi everyone,

I am building a procurement vendor agent in Microsoft Copilot Studio using the new agent experience and have connected Dynamics 365 Business Central MCP as a tool.

The MCP connection appears to be working correctly. The connection shows as active, authentication is configured as Maker, and the available Business Central tools are enabled. For example, I have tools for retrieving vendor-offered prices and item-vendor details.

However, when I test the agent with a request such as

“Get Vendors List”

the agent does not invoke the Business Central MCP tool. Instead, it responds with something similar to

“I only have bash and file tools available, so I should check the workspace/data directory…”

It then says that there is no connector/search tool available and that it cannot retrieve the Business Central data.

I also noticed the response contains an instruction such as:

skill: search-before-answer

However, I have no Skills configured in the agent. The only configured tool is Dynamics 365 Business Central MCP.

My agent instructions explicitly state that it is a Dynamics 365 Business Central procurement agent, that it must use real Business Central data, and that it should use the configured tools when analyzing vendors, prices, quality, delivery, etc.

Why is the new Copilot Studio experience referring to “bash and file tools” and search-before-answer when those are not configured in my agent? Is this coming from the new agent orchestration/harness, and how can I make the agent correctly invoke the Business Central MCP tools?

I would also like to understand whether MCP tools need specific descriptions/tool names for the new orchestration experience to select them correctly.

Thanks!

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Model context protocol

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Sam_Fawzi 1,150 Super User 2026 Season 1 on at

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Hi @CU30060856-1

Taking your questions in order.

Why bash, file tools, and search-before-answer. Those are not yours and nothing is misconfigured. The new experience runs on the GitHub Copilot harness, which is a code-execution harness with its own built-in toolset, including a file system and a bash environment. The docs reference files the agent creates during a turn being capped at 10 MB, which is the same file system your agent is talking about. search-before-answer is a built-in skill of that harness, not something you added. What you are seeing in that screenshot is the harness's reasoning trace, not its final answer.

Why it is not calling your MCP tool. Two possibilities and they need different fixes.
First, do not treat the agent's self-report as evidence. Models are unreliable narrators about their own configuration and will often claim they have no tools when tools are wired correctly. Test with a task instead of a question, and watch whether it attempts a call.
But your reasoning trace says it does not see the tools at all, and that matches a report from 3 September with an identical presentation, same BC MCP server, same Maker auth, same search-before-answer line, where the user confirmed the server works on Standard and not here. So this may not be your configuration.

Things worth checking on your side first, in order:

Individual tool toggles. Open the MCP server in the components panel and confirm the specific tools are switched on. The toggle in the header row is a select-all state, not an enable. This was the actual cause in one of the earlier reports.

Switch Authentication mode from Maker to User and reconnect. Cheap to rule out.

Republish, then test in a fresh conversation.

On your last question, yes, descriptions matter and this is documented. The Learn troubleshooting guidance for the new experience says directly that if a tool is not being invoked you should review its description, because vague descriptions can prevent the orchestration runtime from selecting the tool. Tool name and description are described as critical, and your agent instructions also influence when tools are used. Worth doing regardless.
That said, description tuning only helps when the tools are visible but not chosen. If the model genuinely cannot see them, no description will fix it, which is why I would settle the toggles and auth first.
One limit worth knowing. MCP servers count against the total number of tools an agent can host, and the number of MCP server instances that can run concurrently in one conversation is capped. Not your issue with a single server, but relevant if you add more later.
If the toggles and auth come back clean, raise it with support and reference that this is now the third community report of the same behaviour on Business Central MCP under the new experience. Post back either way, since a definitive answer would help several people.

References:

https://learn.microsoft.com/en-us/microsoft-copilot-studio/agents-experience/tools-manage
https://learn.microsoft.com/en-us/microsoft-copilot-studio/agents-experience/tools-overview
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Mohsin Ali 1,075 on at

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Hello @CU30060856-1 - I am suspecting that you haven't clearly mention in your instructions to which tool the agent should use to pull BC details i.e Get Vendor List.

I would recommend adding instructions in following way:

You are Procurement Agent; use tool /RefToBCTool to get the vendor lists and respond.
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Ashlesha-MSFT Microsoft Employee on at

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Hi CU30060856-1
The references to files, sandbox operations, or skills can be associated with the GitHub Copilot harness used by the new agent experience. However, the agent’s statement about which tools it has should not by itself be treated as proof that the Business Central MCP tools are unavailable. Please verify the actual invocation through the activity trace.

Please check the following:

Open Build → Tools → Dynamics 365 Business Central MCP.

Confirm each required MCP tool is individually enabled.

Verify that the MCP connection and authentication are valid.

Confirm that the server actually exposes a tool capable of listing vendors. Tools for vendor prices or item-vendor details might not support a general “Get Vendors List” request.

Review the exact tool name and description. Microsoft documentation states that these are critical to tool selection and that vague descriptions can prevent invocation.

Update the agent instructions to reference the exact exposed tool and its purpose, for example: For requests to retrieve Business Central vendors, use the
<exact MCP tool name> tool. Do not answer from general knowledge.
If that tool is unavailable or returns an error, report the error.

Save, republish, start a fresh Preview conversation, and use a request matching the tool’s documented capability.

Open the activity trace and verify whether the MCP tool was offered, invoked, which arguments were supplied, and what it returned.