The practical answer
An AI agent is software that uses a model to choose or sequence actions through tools. The model is only one component. A production system also needs permissions, state, validation, monitoring, and a clear way to stop or escalate.
Build it in this order
1. Define one bounded outcome
Write the exact trigger, allowed actions, required evidence, and success condition. Avoid starting with a broad goal such as “automate support.” A safer first workflow might classify a ticket, draft a reply from approved sources, and wait for human approval.
2. Decide whether an agent is necessary
Use a deterministic workflow or a single model call when the sequence is known. Add agentic planning only when the system genuinely needs to choose among tools or adapt the next step.
3. Design tools as narrow APIs
Each tool should have typed inputs, explicit authorization, predictable errors, timeouts, and idempotency where possible. Keep destructive, financial, external-communication, and permission-changing actions behind deterministic checks and approval.
4. Store state outside the prompt
Record workflow status, tool results, approvals, retries, and evidence in durable storage. Do not rely on chat history as the system of record.
5. Add evaluation before launch
Test representative tasks, unsafe inputs, prompt injection, tool failure, ambiguous requests, and model changes. Measure task success, unsupported claims, bad tool calls, latency, cost, and human-review effort.
6. Operate it like software
Use logs, traces, budgets, rate limits, alerts, rollback, and incident procedures. Pin versions where supported and re-run evaluations before changing the model, prompt, tools, or retrieval pipeline.
The safest first release is narrow, observable, reversible, and honest about where a human remains responsible.
Fact-check sources
- NIST AI Risk Management Framework
- OWASP Top 10 for Agentic Applications 2026
- OpenAI API models and pricing
- Anthropic current model overview
- Google Gemini model catalog
- LangGraph official documentation
Sources and product documentation can change. Recheck time-sensitive pages on the publication date.