[BUG] Transcribing that should have been reproduced verbatim

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?

I'm running Claude Code : 2.1.140

Claude transcribes values from tool results into response text rather than reproducing them verbatim, introducing transcription errors (e.g. UUID characters transposed).

As a result it ended up getting one character wrong in a 32-character key.

What Should Happen?

this information should have been copy/pasted rather than transcribed

Error Messages/Logs

The error was in the product I'm developing as I ended up using the wrong access key.

Steps to Reproduce

Something like this would be a clean reproduction:

Steps:

1. Run any command that returns a UUID or other exact string via a tool — e.g.

uuidgen via Bash, or an API call that returns a token

1. Ask Claude to present that value as a URL or formatted string in its response

text

1. Compare the value in Claude's response to the value in the tool result

What to check: Any character transposition, substitution, or truncation between the
tool output and what appears in Claude's reply.

Why it's reliably reproducible: The error class is transcription of exact data from
tool results into response prose. It's most likely to surface with long opaque
strings (UUIDs, hashes, tokens) where there's no semantic signal to catch a mistake
— the same reason humans make this error.

Suggested title: Claude transcribes exact values from tool results rather than
reproducing them verbatim, introducing transcription errors

Suggested severity note: Low friction in most cases, but potentially serious where
the output is used in security tokens, medical record IDs, financial references, or
any context where an incorrect value causes silent failure or data corruption.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.140

Claude Code Version

claude-sonnet-4-6

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Xterm

Additional Information

_No response_