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Harness engineering
The model is the engine. The harness is the car.
The Harness
System Prompt
Context Mgmt
Model
Tool Orch
Error Recovery
System Prompt
Instructions the model receives before the user speaks.
You are a research analyst.
Always cite sources.
Never fabricate data.
Always cite sources.
Never fabricate data.
Context Management
Decides what fits in the model's limited memory window.
Tokens used32K / 128K
Tool Orchestration
Routes the model to the right tool at the right time.
searchreadwrite
Error Recovery
Detects failures and retries with a different approach.
Attempt 1
Attempt 2
Same model, different harness
Basic harness
No system prompt
No tools
No error handling
Output
Generic, sometimes wrong, no sources
Production harness
System prompt + constraints
Tool access via MCP
Retry + fallback logic
Output
Specific, cited, reliable