[BUG] Read tool's PDF support requires poppler-utils but it's undocumented, usually absent, and not detected after install

What's Wrong?

The Read tool's description says "This tool can read PDF files (.pdf)", but PDF reading depends on poppler-utils (specifically pdftoppm), which:

1. Is not installed by default in common development environments — In our case, a container based on node:22-bookworm did not have it. It is not part of coreutils and requires explicit installation.
2. Is not documented as a requirement — The system requirements page does not mention poppler-utils. The Read tool's description promises PDF support with no caveats.
3. Is not detected after installation — After running sudo apt-get install poppler-utils, which pdftoppm succeeds (/usr/bin/pdftoppm), but the Read tool still returns "pdftoppm is not installed".

What Should Happen?

Either:

• Bundle or auto-install the dependency so PDF reading works out of the box, or
• Document it as a system requirement for PDF support, or
• At minimum, detect it correctly after installation without requiring a restart

Error Messages/Logs

pdftoppm is not installed. Install poppler-utils (e.g. `brew install poppler` or `apt-get install poppler-utils`) to enable PDF page rendering.

This message is returned to the model but not shown in the TUI (filed separately as #23699).

Steps to Reproduce

1. Start Claude Code in an environment without poppler-utils (tested in a container based on node:22-bookworm)
2. Ask Claude to read a PDF file
3. Read fails with "pdftoppm is not installed"
4. Run sudo apt-get install poppler-utils
5. Verify: which pdftoppm → /usr/bin/pdftoppm ✅
6. Ask Claude to read the same PDF again
7. Read fails again with the same error

Model: Opus

Is this a regression?: I don't know

Claude Code Version: 2.1.33

Platform: Anthropic API

Operating System: Ubuntu/Debian Linux

Terminal/Shell: iTerm2

Additional Information

• Related: #23699 (Read tool errors are not shown in TUI)
• The workaround is curl + pdftotext + Read on the resulting text file — 3 tool calls for what should be a single Read

✍️ Author: Claude Code with @carrotRakko (AI-written, human-approved)