Gemini Second Opinion

Use Gemini to get an independent review from a model with a 1M+ token context window.

Invocation

Use -p for non-interactive (headless) mode. Always use -o text for plain text output.

Prefer telling Gemini to read files directly over piping via stdin. Gemini can read files within the project workspace on its own, and stdin truncates at 8MB.

# PREFERRED: Tell Gemini to read files itself (non-interactive)
gemini -p "Read the files in /path/within/project/ and review them for bugs" -o text

# OK for small content: pipe via stdin
git diff main..HEAD | gemini -p "Review this diff for issues" -o text

Workspace Sandbox

Gemini is sandboxed to the project directory. It cannot read files outside the workspace, even via symlinks.

If files live outside the project (e.g., ~/.claude/), copy them into the project first, then clean up after:

cp -r ~/.claude/some-data /path/to/project/.tmp-data
gemini -o text "Read the files in /path/to/project/.tmp-data/ and analyze them"
rm -rf /path/to/project/.tmp-data

Workflow

1. Gather context: Identify the files, plans, or diffs Gemini needs
2. Ensure accessibility: If files are outside the workspace, copy them in
3. Compose a focused prompt: Be specific about what to review and what feedback you want
4. Invoke Gemini: Tell it to read files directly, or pipe small content via stdin. Always use -p and -o text
5. Clean up: Remove any temporary copies
6. Report findings: Present Gemini’s feedback to the user with your own assessment of which points are valid

Prompt Guidelines

• State the review goal explicitly (e.g., “find logical errors”, “evaluate scalability”, “check for missing edge cases”)
• Include constraints or requirements Gemini should check against
• Ask for structured output (numbered issues, severity levels) for actionable feedback
• For large volumes of files, tell Gemini to read the directory rather than listing each file