Agents & tools
Human in the loop
Definition
Human in the loop means inserting a person at decision points in an automated workflow — typically to approve consequential actions or review low-confidence outputs before they take effect.
Full automation is attractive but appropriate only where errors are cheap and reversible. For anything that sends external communication, moves money, deletes data or makes a commitment, a review step is standard practice.
The efficient pattern is confidence-based routing. Let the system handle clear cases automatically and escalate ambiguous ones. You keep most of the throughput benefit while capping the damage from confident mistakes.
Design the review to be fast. A gate that takes two minutes per item will be bypassed under pressure; one that takes five seconds will be used.
Related terms
Guardrails
Guardrails are the constraints that keep an AI system inside acceptable behaviour — input validation, output filtering, topic restrictions, action limits and human approval gates.
AI agent
An AI agent is a system where a model plans and takes actions through tools in a loop, rather than producing a single response. It decides what to do next, does it, observes the result, and continues until the goal is met.
Confidence score
A confidence score estimates how reliable an output is. Language models do not natively produce calibrated confidence, and asking a model how sure it is yields poorly calibrated self-assessment.
ReAct pattern
ReAct (Reason + Act) is the core agent loop: the model reasons about what to do, takes an action via a tool, observes the result, then reasons again. It repeats until it can answer.
MCP (Model Context Protocol)
MCP is an open standard for connecting AI models to external tools and data sources. It replaces bespoke per-integration code with one protocol any compatible client can use.
Tool use
Tool use is a model invoking external capabilities — search, code execution, database queries, APIs — to do things it cannot do from parameters alone, such as fetching current data or performing exact arithmetic.
Put this into practice
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