API Error 400: eager_input_streaming parameter not permitted in Claude Code VS Code Extension v2.1.72

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Description

The Claude Code VS Code extension (v2.1.72) is sending an invalid parameter eager_input_streaming to the Anthropic API, causing all chat prompts to fail with a 400 error.

Environment

• Extension Version: 2.1.72
• VS Code Version: 1.111.0
• OS: macOS (Darwin 25.3.0, arm64)
• Claude Model: Claude Opus 4.6 / Sonnet 4.5
• Date Encountered: March 10, 2026

Actual Behavior

All prompts fail with a 400 error indicating that eager_input_streaming is not a permitted parameter in the API request.

Workaround

Using the Claude Code CLI (claude code command) instead of the VS Code extension works without issues.

Suggested Fix

The eager_input_streaming parameter should either be:

1. Removed from the extension until it's supported by the Anthropic API, or
2. Made conditional based on API version/capability detection, or
3. Properly documented if it requires specific API tier access

Impact

This bug makes the VS Code extension completely unusable for all users on v2.1.72.

What Should Happen?

Expected Behavior

Chat prompts should execute successfully and return Claude's response.

Error Messages/Logs

Error Message

  API Error: 400 {"errorMessage":"{"message":"tools.0.custom.eager_input_streaming: Extra inputs are not permitted"}\n","errorCode":"PROXY_LLM_ERROR","date":"2026-03-10T06:40:39.147109546Z","statusCode":400,"errorArgs":{"provider":"anthropic"}}

Steps to Reproduce

Steps to Reproduce

1. Install Claude Code VS Code extension v2.1.72
2. Open any project in VS Code
3. Open Claude Code chat panel
4. Send any chat prompt
5. Error occurs immediately on API request

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

v2.1.70

Claude Code Version

Claude Code VS Code extension v2.1.72

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Additional Context

• The error occurs with every single prompt, not just specific ones
• The Claude Code CLI (claude code in terminal) works perfectly fine
• Extension was updated to v2.1.72 from the VS Code marketplace
• Clearing extension cache did not resolve the issue
• The parameter tools.0.custom.eager_input_streaming appears to be automatically added by the extension