Tool parameter validation bug - required parameters not recognized

Environment

• Platform (select one):
  • Anthropic API
  • AWS Bedrock
  • Google Vertex AI
  • Other:
• Claude CLI version:
• Operating System: Linux 5.15.146.1-microsoft-standard-WSL2
• Terminal: WSL2

Bug Description

Tool parameter validation system is incorrectly rejecting valid parameters as missing. Multiple tools (Write, Bash) are failing with "InputValidationError: [Tool] failed due to the following issue: The required parameter [parameter_name] is missing" even when the required parameters are properly provided in the function call.

Steps to Reproduce

1. Attempt to use the Write tool with both required parameters: Write tool call with:

• file_path: "/mnt/c/[REDACTED]/test.html"
• content: "any content string"

2. Attempt to use the Bash tool with required command parameter: Bash tool call with:

• command: "echo test"
• description: "test command"

3. Both tools return parameter validation errors

Expected Behavior

Tools should accept properly formatted parameters and execute successfully when all required parameters are provided according to the tool schema.

Actual Behavior

Tools consistently fail with parameter validation errors:

• InputValidationError: Write failed due to the following issue: The required parameter 'content' is missing
• InputValidationError: Bash failed due to the following issue: The required parameter 'command' is missing

This occurs even when parameters are clearly present and properly formatted in the function calls.

Additional Context

• Issue appeared suddenly during an active session
• Affects multiple tools, suggesting a systemic parameter validation problem
• Simple test calls (like Write with just file_path and "test" as content) work intermittently
• More complex parameter combinations consistently fail
• This appears to be a regression in the parameter parsing/validation system
• The issue prevents basic file operations and significantly impacts functionality
• Session context: Working directory /home/[REDACTED]/[REDACTED], model claude-sonnet-4-20250514