MCP tool call with Object type parameter does not work

[inv-Eldho]

What happened?

Ongoing Issue with add_fields Tool – Properties Being Passed as Empty

Hi,

We are experiencing the same issue again when attempting to pass field properties from LibreChat to MCP. The properties object becomes empty during the process, specifically when using the add_fields tool.

Prompt i tried is :
Add these field into app

{
"app": 810,
"properties": {
type: "SINGLE_LINE_TEXT"
code: "minutes_id",
label: "minutes_id" }
}
}
Here’s the request we’re making:

Running add_fields tool

{
"app_id": 810,
"properties": {
"minutes_id": {
"code": "minutes_id",
"type": "SINGLE_LINE_TEXT",
"label": "minutes_id",
"required": false
}
}
}
Result:
We continue to encounter a technical issue when trying to add the minutes_id field to the app. The system returns the following error:

"properties requires at least one field definition"

Version Information

74d8a38

Steps to Reproduce

Using the model apac.anthropic.claude-3-7-sonnet-20250219-v1:0.

I'm using the MCP server for Kintone (dev), specifically the kintone-mcp-server.

My workflow is:
Prompt: Create an app named "Project Tracking"
Executed tool: create_app()
Prompt: Create a record in the app that contains a drop-down list field.
Executed tool: add_fields()

After that, the add_fields() tool was run again with the following input:

{
"app_id": 820,
"properties": {
"status": {
"type": "DROP_DOWN",
"code": "status",
"label": "Status",
"options": {
"Not Started": {
"label": "Not Started",
"index": "0"
},
"In Progress": {
"label": "In Progress",
"index": "1"
}
}
}
}
}
Issue:
The error I receive is:

properties には少なくとも1つのフィールド定義を指定する必要があります。
Translation: "You must specify at least one field definition in properties."
We also tested the latest changes in this #8381, but it does not fix the issue.

What browsers are you seeing the problem on?

No response

Relevant log output

None

Screenshots

Thank you for understanding !

Code of Conduct

• I agree to follow this project's Code of Conduct

[danny-avila]

I will need to make a kintone account to test, but I can see from the tool definition that it is incorrectly formed and primarily an issue with the kintone mcp server.

The issue is that the properties field in the Kintone tool definition is specified as type: 'object' without any additionalProperties setting, which causes Zod to create a strict empty object schema that strips out all the field definitions you're trying to pass.

We can fix this edge case to treat these "bare object" schemas (object type with no properties defined and no additionalProperties) as passthrough schemas, allowing dynamic properties to flow through as intended. This ensures your field definitions like minutes_id are properly sent to the Kintone API instead of being stripped to an empty object.

However, this seems to be a malformed tool definition first and foremost.

[danny-avila]

Closed by #8637