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[Bug] MCP node passes wrong data format to MCP server for the parameters #3678

@xyziven

Description

@xyziven

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MaxKB Version

1.10.8 LTS & 2.0.0

Problem Description

Environment: Quickchart MCP Server

It returns Exception when set data in the format like this in parameter(customr or reference variable):
[{"label": "Sales","data":[65,59,80],"backgroundColor":["#FF6384","#36A2EB","#FFCE56"]}]

Image

From MCP Server side, we observed the request from the log. The dataset was captured in the screenshot below, which is the cause of the problem.
"[{\"label\": \"Sales\",\"data\":[65,59,80],\"backgroundColor\":[\"#FF6384\",\"#36A2EB\",\"#FFCE56\"]}]"

Image

The MCP call completed successfully if the server side receives the data in the format like this:
[{"label":"Sales","data":[65,59,80],"backgroundColor":["#FF6384","#36A2EB","#FFCE56"]}]

Image

Steps to Reproduce

  1. Have MCP server setup
  2. Create Workflow with MCP client node
  3. Set the parameter of the MCP client node with data format or variable similar to what described above.

The expected correct result

The MCP call is expected to complete successfully.

Related log output

Refer to the information in problem description.

Additional Information

If quest the mcp call directly using python with right data format, it completes successfully.

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