execute_zapier_write_action / execute_zapier_read_action fail with "Invalid input: expected record, received string" (path: params)

Summary
Both execute_zapier_write_action and execute_zapier_read_action (Zapier MCP connector) fail 100% reproducibly with:

MCP error -32602: Input validation error: Invalid arguments for tool execute_zapier_write_action: [
  {
    "expected": "record",
    "code": "invalid_type",
    "path": ["params"],
    "message": "Invalid input: expected record, received string"
  }
]

Repro
Call either tool with the normal shape, e.g.:

{"selected_api": "YouTubeV4CLIAPI", "action": "upload_video", "tool_name": "youtube_upload_video", "params": {"video": "...", "title": "..."}}

Fails identically regardless of: flat vs nested params, ASCII vs Unicode/emoji content, which underlying app/action (tried YouTube upload_video, Instagram Graph API raw request, GitHub get_file_contents/create_issue).

What we ruled out

• Not an auth issue: inspect_zapier_actions (same MCP server) continues to work fine throughout; a genuine separate "connector requires authentication" error occurred once and was fixed by disconnecting/reconnecting the Zapier connector at claude.ai — but this params error persisted unchanged after that fix.
• Not app-session state: full app restart did not change the behavior.
• Not stale action schema: disabling and re-enabling the specific Zapier action (fresh schema registration) did not change the behavior.
• Not content-specific: tested minimal ASCII-only params and full Korean+emoji params, identical failure.

Impact
Completely blocks any workflow that needs execute_zapier_write_action/execute_zapier_read_action — e.g. publishing generated video to YouTube/Instagram via Zapier's Instagram-for-Business/YouTube CLI APIs, or even filing this very issue via GitHub's create_issue action (had to fall back to gh issue create from a terminal instead).

Environment: Claude Code desktop app (Cowork/session context), Windows 11, Zapier MCP connector.

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