Giving Agents a Private Thinking Space

Humans don't jump straight to answers - we mutter to ourselves, scribble notes, and reason through problems. The Inner Monologue pattern gives agents the same capability.

How It Works

Instead of the agent directly outputting actions, you create a structured format where the agent must write out its reasoning before deciding what to do:

## Agent Scratchpad

**Current Goal:** Find the user's order status
**What I Know:**
- User provided order ID: #12345
- I have access to the orders_db tool
**What I Need To Do:**
- Query the database for order #12345
- Check if the order has shipped
**My Confidence:** 9/10 - this is straightforward
**Decision:** Call orders_db.get_status("12345")

Why This Works

Implementation Patterns

Pattern 1: Structured XML Scratchpad

System Prompt:
"Before every action, write your reasoning inside
<scratchpad> tags. Include:
1. Current sub-goal
2. Information gathered so far
3. Next planned action and why
4. Confidence level (1-10)
</scratchpad>
Then emit your action."

Pattern 2: Extended Thinking (Claude)

Claude's native Extended Thinking feature automates this pattern. By enabling thinking: {type: "enabled", budget_tokens: 4000}, Claude shows its reasoning in a dedicated thinking block before the final response - no custom prompting needed.

Pattern 3: Separate Reasoning Model

Use a smaller, cheap model (like Haiku) as the "inner monologue" step, then pass its analysis to the main model for the final decision. This separates reasoning cost from action cost.

Scratchpad vs Extended Thinking