Todoist MCP – Read tools work, write tools fail with SystemError

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Posted on by DT-16072043-0

I am testing the official Todoist MCP server in Microsoft Copilot Studio using a clean test agent.

Endpoint:

https://ai.todoist.net/mcp

The MCP server initializes successfully and returns the full tool catalogue. Read tools work correctly:

- user-info returns the correct Todoist account details.

- find-projects returns the correct Inbox project and project ID.

However, write tools fail consistently.

Example:

Prompt: "Create a task called Test Task"

Copilot Studio selects the correct MCP tool:

add-tasks

It binds the payload correctly:

{

"tasks": [

{

"content": "Test Task"

}

]

}

But execution fails immediately with:

{

"state": "failed",

"observation": {},

"executionTime": "00:00:00",

"ErrorCode": "SystemError"

}

The same official Todoist MCP server works in Claude, including successful task creation using the same Todoist account.

This appears to suggest that Copilot Studio can initialize and use the Todoist MCP server for read operations, but fails when executing write tools. Is this a known limitation or bug in Copilot Studio’s MCP runtime?

Categories:

Model context protocol

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Prasad-MSFT Microsoft Employee on at

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Thanks for sharing the detailed repro. A few questions that might help narrow down whether this is specific to the Todoist MCP server or the Copilot Studio MCP runtime:

Does the issue occur with all Todoist write tools (for example, update, close, or delete), or is it only add-tasks that fails?

Have you tried connecting to a different MCP server that supports write operations? If so, do write tools work there?

If you have access to the Todoist MCP server logs, do you see the write request reaching the server at all, or does the failure happen before the request is sent?

The fact that the server initializes correctly, the tool is selected, the payload is bound as expected, and read operations succeed makes it seem like the failure is happening during tool execution rather than tool selection or parameter binding.

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CU20040759-0 2 on at

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Since the same Todoist MCP server handles writes correctly in Claude, the issue isn’t with Todoist but with Copilot Studio’s execution of write operations. In other words, it’s a known bug/limitation on the Copilot side rather than a misconfiguration on your end.
NIPR com

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