kimi-cu MCP tool "js_reset" ships inputSchema without "properties", LM Studio rejects every request with 400 invalid_type #4177

Summary

The js_reset tool exposed by the kimi-cu MCP server (Kimi Computer Use plugin) has an inputSchema of:

{"type": "object", "additionalProperties": false}

It is missing the properties key. OpenAI's API tolerates this, but LM Studio's OpenAI-compatible server validates tools[] with zod and requires function.parameters.properties to be present, so every chat request fails with HTTP 400 before reaching the model.

Environment

• kimi-cu plugin: 0.6.3 (~/.kimi-code/plugins/managed/kimi-cu/kimi.plugin.json)
• KimiCU.app: 0.6.6 (/Applications/KimiCU.app, bundle id ai.kimi.cu)
• macOS, provider type openai, base_url http://127.0.0.1:1234/v1 (LM Studio), model qwen/qwen3.5-9b

Error

400 "[
  {
    "code": "invalid_type",
    "expected": "object",
    "received": "undefined",
    "path": [25, "function", "parameters", "properties"],
    "message": "Required"
  }
]"

Tool index 25 (0-based) in the request is exactly mcp__kimi-cu__js_reset. I extracted the 47-tool payload from the session wire log: it is the only tool whose parameters lacks properties.

Minimal reproduction (against LM Studio directly, no kimi-code involved)

# tools = [{"type": "function", "function": {"name": "js_reset",
#   "description": "reset",
#   "parameters": {"type": "object", "additionalProperties": False}}}]
# POST /v1/chat/completions  ->  400 with the exact zod error above

# Same tool with "properties": {} added  ->  200 OK

Expected behavior

js_reset's inputSchema should be:

{"type": "object", "properties": {}, "additionalProperties": false}

An object schema without properties is non-idiomatic JSON Schema and breaks strict validators. Two possible fixes:

1. Fix the schema in the KimiCU MCP server (the tool definition lives in the compiled /Applications/KimiCU.app binary, so users cannot patch it themselves).
2. Defensively, kimi-code could normalize MCP tool schemas before sending them to OpenAI-compatible providers (fill missing properties: {} for object schemas) — related to the schema-sanitization gap discussed in MCP tool schema validation fails with HTTP 400 ("moonshot flavored json schema") due to missing schema sanitization in new CLI #792.

Workaround

Disable the kimi-cu plugin, or remove "js_reset" from enabledTools in kimi.plugin.json; requests to LM Studio then succeed.