Updated: October 6, 2026 · Source-first reference130 documented agents & platforms · No paid rankings

AgentenCode Knowledge

How do AI agents work?

The model proposes actions, but the surrounding system decides what information, tools and permissions are available and how each action is executed or approved.

Direct answer

AI agents typically operate in a loop: understand the goal, collect context, plan a next step, use a tool, observe the result, update state and decide whether to continue.

1. Goal and context

The agent begins with a user request, system objective or event. It combines that goal with available context: conversation history, files, retrieved documents, application state or structured business data.

Good context engineering matters because an agent can only reason from what it can see. Too little context produces blind spots; too much irrelevant context can reduce reliability and increase cost.

2. Planning the next step

The model may create an explicit plan or choose one action at a time. Some systems use a planner-executor pattern; others rely on iterative tool calls without a visible plan.

Planning should remain bounded. A production agent usually benefits from clear stopping conditions, maximum step counts and rules that define when it must ask a human rather than continue on its own.

3. Tool use

Tools are how an agent leaves the chat interface. A tool can search the web, read a database, execute code, create a ticket, send a message or call another service.

The tool layer should validate inputs and enforce permissions. The model should not be treated as the access-control system. Credentials, allowlists, schemas and approval rules belong in the surrounding software.

4. Observe and adapt

After a tool runs, the agent receives a result and decides what it means. It may need to retry, choose another tool, ask for clarification or revise the plan.

This feedback loop is what makes agents flexible, but it also creates new failure modes. A bad result can lead to another bad action unless the system validates outputs and limits compounding errors.

5. Memory and state

Working state helps the agent track progress during a run. Longer-term memory can preserve user preferences, facts or task state across sessions. Retrieval systems can provide external knowledge without turning every retrieved item into permanent memory.

Memory needs retention, ownership and deletion rules. A remembered instruction can influence future actions, so memory should be treated as data with security implications.

6. Control and observability

Identity, permissions and human approval determine which actions are actually possible. Tracing and logs show what the agent attempted, which tool ran, what input it received and what output was returned.

Without observability, debugging and governance become difficult. A production agent should make it possible to reconstruct important actions and distinguish model reasoning from tool execution and external state changes.

Failure and recovery

Agents can fail because of missing context, tool errors, ambiguous instructions, prompt injection or incorrect assumptions. Robust systems handle these failures explicitly through retries, fallbacks, escalation and rollback rather than simply continuing indefinitely.

Evaluations should include realistic failure cases, not only successful demonstrations. The operational quality of an agent is defined by how it behaves when the world does not match its expectations.

Frequently asked questions

Does an AI agent always create a plan?

No. Some agents plan explicitly; others choose the next action iteratively.

What makes tool use safe?

Permissions, input validation, scoped credentials, approvals and logging around the tool call—not the model alone.

Why are logs important?

They make actions traceable and help teams understand failures, policy violations and unexpected tool behavior.

Technical deep dive

The agent loop: observe, decide, act, then evaluate again.

A production agent is not one prompt. The application maintains state, provides a goal and context, exposes permitted tools and processes the model response. If the model selects a tool, the application executes it and returns the result or error. The next reasoning turn starts from that new state. The loop ends only when the goal is met, a budget or time boundary is reached, an error stops execution or human approval is required.

1. Goal & context

System rules, the user goal, relevant data and previous steps form the working context. Long tasks require deliberate context compression, summarization or selective retrieval from external memory.

2. Tool selection

Tools are exposed with names, descriptions and structured parameters. With function calling, a JSON schema defines allowed arguments; the application validates the data and executes the function outside the model.

3. Observation

Tool results, errors and changed system state are returned to the model. The agent can use the observation to choose the next step or change strategy.

4. Stop & approval

Autonomy needs termination conditions: maximum steps, cost budget, time limit, prohibited actions and human approval for irreversible or high-impact operations.

Workflow or agent?

Use only as much autonomy as the task requires.

Anthropic distinguishes workflows from agents: workflows follow code-defined paths, while agents dynamically direct their process and tool use. Predictable tasks often benefit from fixed paths because they are cheaper and easier to test. Model-directed autonomy is more useful when the solution path is open-ended and later steps depend on intermediate results.

Prompt chaining

Several explicit steps run in sequence. Useful when every stage can be checked and the path is known in advance.

Routing

A classifier or model selects the right specialized path, tool set or model for the request.

Orchestrator–worker

An orchestrator decomposes a task and delegates subtasks to workers. This is useful when the required subtasks emerge only at runtime.

Evaluator–optimizer

A generator creates an output, an evaluator checks it against explicit criteria and triggers another iteration when needed.

Context, security & evals

Three production problems that simple demos hide.

Context management

More steps mean more tokens, cost and noise. Production systems need rules for what stays in active context, what is summarized and what is retrieved on demand from memory or external systems.

Indirect prompt injection

When an agent reads web pages, email, files or repositories, external content can contain malicious instructions. External data should not have the same authority as system rules, tool privileges should be minimal and sensitive actions should require separate approval.

Evals over intuition

Agents should be evaluated across complete trajectories: did they reach the goal, select appropriate tools, avoid prohibited actions, handle failures and stay within cost and latency limits?

Identity & authorization

An agent should act clearly on behalf of a user, service account or distinct agent identity. Permissions and delegation need to match that identity model and remain auditable.