| name | external-llm-consulting |
| description | Get architecture and design second opinions from external LLMs (OpenAI Codex, Google Gemini) via their CLIs. Use when you need alternative perspectives on design decisions, model selection, or structured comparison of approaches. |
| allowed-tools | Bash Read Grep Glob |
External LLM Consulting
Audience: Developers seeking alternative AI perspectives on architecture and design decisions.
Goal: Invoke external LLM CLIs in read-only/sandbox mode to get structured second opinions, then present results for comparison with Claude's perspective.
When to Use
- Validating architectural choices with diverse AI perspectives
- Exploring alternative approaches Claude might not consider
- High-stakes design decisions benefiting from model diversity
- Surfacing blind spots through cross-model analysis
General Workflow
- Gather relevant context (CLAUDE.md, AGENTS.md, existing code patterns, constraints)
- Formulate a focused prompt with context, specific questions, and structured output request
- Execute the external CLI in sandbox/read-only mode
- Parse and structure the response for comparison
Codex Consulting
Prerequisites
- Codex CLI installed (
codex --version to verify)
- OpenAI authentication configured (
codex login)
Available Models
| Model | Use Case | Cost |
|---|
gpt-5.1-codex-mini | Fast, cost-effective (~4x more usage) | Low |
gpt-5.1-codex | Balanced, optimized for agentic tasks (default) | Medium |
gpt-5.1-codex-max | Maximum intelligence for critical decisions | High |
Parse model from prompt if specified (e.g., "using codex-mini, analyze..." or "model: gpt-5.1-codex-max").
CLI Execution
Run Codex in read-only sandbox mode:
codex exec --sandbox read-only --model <model> "<prompt>"
Important flags:
--sandbox read-only - Prevents any code modifications--model <model> - Model to use (default: gpt-5.1-codex)
For complex prompts, use heredoc:
codex exec --sandbox read-only --model gpt-5.1-codex "$(cat <<'EOF'
Context: [codebase context]
Question: [specific architectural question]
Please provide:
1. 2-3 alternative approaches
2. Trade-offs for each approach
3. Your recommendation with reasoning
EOF
)"
Codex Error Handling
| Error | Resolution |
|---|
| CLI not found | Install: npm install -g @openai/codex then codex login |
| Auth failed | Run: codex login |
| Timeout (>2 min) | Report partial results or simplify the query |
Gemini Consulting
Prerequisites
- Gemini CLI installed (
gemini --version to verify)
- Google authentication configured
Available Models
| Model | Use Case | Cost |
|---|
gemini-2.5-flash | Fast, cost-effective consulting | Low |
gemini-2.5-pro | Balanced reasoning | Medium |
gemini-3.0-pro-preview | Latest Gemini 3 Pro (default) | Medium |
Parse model from prompt if specified (e.g., "using flash, analyze..." or "model: gemini-3.0-pro-preview").
CLI Execution
Run Gemini in sandbox mode:
gemini --sandbox --output-format text --model <model> "<prompt>"
Important flags:
--sandbox - Prevents any code modifications--output-format text - Returns plain text (vs json/stream-json)--model <model> - Model to use (default: gemini-3.0-pro-preview)
For complex prompts, use heredoc:
gemini --sandbox --output-format text --model gemini-3.0-pro-preview "$(cat <<'EOF'
Context: [codebase context]
Question: [specific architectural question]
Please provide:
1. 2-3 alternative approaches
2. Trade-offs for each approach
3. Your recommendation with reasoning
EOF
)"
Gemini Error Handling
| Error | Resolution |
|---|
| CLI not found | Install: npm install -g @anthropic-ai/gemini-cli / See https://github.com/google-gemini/gemini-cli |
| Auth failed | Run gemini and follow authentication prompts |
| Timeout (>2 min) | Report partial results or simplify the query |
Prompt Formulation
Create a focused prompt that:
- Provides necessary context about the codebase
- Asks specific questions about the decision
- Requests structured output (options with trade-offs)
Include relevant sections from CLAUDE.md/AGENTS.md and any project constraints mentioned in the user's request.
Output Format
## [Codex/Gemini] Consulting Results
**Query:** [Original question/topic]
**Model:** [model used] (via [Codex/Gemini] CLI)
### Alternative Perspectives
#### Option 1: [Name]
- **Approach:** [Description]
- **Pros:** [Benefits]
- **Cons:** [Drawbacks]
#### Option 2: [Name]
- **Approach:** [Description]
- **Pros:** [Benefits]
- **Cons:** [Drawbacks]
#### Option 3: [Name]
- **Approach:** [Description]
- **Pros:** [Benefits]
- **Cons:** [Drawbacks]
### Recommendation
[LLM's preferred approach and reasoning]
### Key Insights
- [Insight 1 - something Claude might not have considered]
- [Insight 2]
- [Insight 3]
### Raw Output
<details>
<summary>Full Response</summary>
[Complete unedited response]
</details>
Safety Constraints
- Always use sandbox/read-only mode - Never allow code modifications
- No secrets in prompts - Don't include API keys, credentials, or sensitive data
- Verify responses - External LLM suggestions are opinions, not authoritative answers
