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Distinguish chatbots, workflows, and agents
The distinction is not conversational style, but who selects the next action and whether external state can be changed.
Why this concept became necessary
A Chatbot generates a response to given input. A Workflow executes developer-defined steps and branches and is highly predictable. In an Agent, the model selects the next tool, order, and whether to repeat based on the goal and current observations.
For tasks with known paths, such as simple classification or three-step approval, a workflow is cheaper and more stable. The flexibility of an agent loop justifies its cost only when there are many exceptions and the required information is difficult to predict.
The distinction is not conversational style, but who selects the next action and whether external state can be changed.
Delegates part of the control flow to model judgment and feeds tool results back as the next observation.
Draw the same task as a fixed graph and as a dynamic loop, and mark where the model makes choices.
Follow it through a concrete system
A workflow suits routing customer inquiries to one of three predefined teams because the branches can be written explicitly in code. An agent loop may help with tasks such as incident investigation, where the next log to inspect or hypothesis to test depends on observations. A conversational interface or natural phrasing does not determine this distinction.
When choosing autonomy, consider both the benefit of handling exceptions and the cost of action failures. A person can review a draft answer, but a single bad decision about a refund, account lock, or firewall change can cause real harm. Even within one agent, a hybrid structure that automates reads and suggestions while sending state changes through fixed workflows and approval is often safer.
Selection criteria and failure boundaries
Along with flexibility come more nondeterminism, cost, long-running execution, and unpredictable behavior.
Misconceptions to avoid: It is incorrect to assume that anything using tool calling once is an agent.
Verify it yourself
Draw the same task as a fixed graph and as a dynamic loop, and mark where the model makes choices.
Official sources for this chapter
The technical facts in the text were reviewed against the following primary sources. The author reconstructed the diagrams and comparisons using these materials.
- Anthropic, 「Building Effective Agents」Review date 2026-08-28 · Scope Latest official documentation
- Model Context Protocol, 「Architecture」Review date 2026-08-28 · Scope MCP 2025-06-18