Building Effective Agents
FAQ

Engineering questions on building AI agents

Twelve answers, each linking to a deeper essay. Drawn from People Also Ask observations and reader email.

Oliver Wakefield-SmithBy Oliver Wakefield-Smith, Digital Signet
Last verified April 2026
What is the difference between an AI agent and a workflow?

Anthropic draws the line cleanly. A workflow follows a predefined path; an agent decides the path at runtime. In production this matters because workflows fail predictably, agents fail unpredictably. Most production-grade systems are workflows wearing some agent affordances. We use the word 'agent' specifically when the system can choose its next tool, model, or sub-agent at runtime.

Do I need a framework to build an AI agent?

No, and Anthropic explicitly recommends starting with direct API calls. Frameworks add abstraction that helps once you have multi-pattern composition or persistent state, and adds overhead until you do. Our practice: hand-write the first prototype. Adopt a framework only after the orchestration shape is stable. We use LangGraph in production and tried CrewAI for two months.

Which AI coding agent is best in 2026?

There is no universal answer. We use Claude Code for terminal-based, multi-file work and Cursor for IDE-bound editing. Devin shines on isolated tasks where you want a managed sandbox, and is the most expensive when its planning prompt drifts. The honest comparison rule lives on our claude-code-vs-cursor and devin-vs-claude-code pages.

Is Claude Code worth the cost?

Yes for complex multi-file tasks, no for simple completion. The trick is the structure you put around it before you hit run, not the prompt at run-time. Used unsupervised it is the most expensive coding agent we have used; gated behind a planning step it is the cheapest per resolved task.

What is the cheapest agent pattern at scale?

Prompt chaining, capped at three steps. Each additional step compounds drift super-linearly while compounding cost only linearly, so the cheap-window is short. Beyond three steps the routing pattern wins on cost because routing serialises only the model that needs the work.

Why is OpenClaw growing so fast?

Three reasons. The +9,999,900% YoY signal reflects a low base, not a saturated category. The rebrand history (clawdbot, moltbot) consolidated brand awareness onto a single name. The NVIDIA NemoClaw partnership validated the architecture for engineers reading hardware-vendor blogs. Whether it is safe to run in production is a different question, covered in the OpenClaw review.

Should I use LangGraph or CrewAI?

Pick LangGraph if you expect to scale; pick CrewAI if you expect to ship fast. We use LangGraph in production. We tried CrewAI for two months and moved off because, around five concurrent agents, the role-based coordination overhead becomes the bottleneck. Your project may not hit that ceiling. If it will not, CrewAI is the faster path to a working prototype, and that is genuinely valuable.

What are the most common production agent failure modes?

Five categories, ranked by frequency in our pipeline. Silent drift (agent completes the task, the task is wrong, no exception). Cost cliff (orchestrator-worker spike). Confidence-gate breach (routing fails on a boundary case). Tool-call cascade (tool returns unexpected schema). Context-window blow-out (long-running agent exhausts context, hallucinates from the truncation point).

How many concurrent agents are too many?

Past five, the orchestration overhead starts to dominate the work. Past eight, in our experience, the synchronisation cost exceeds the LLM token cost. This is a measured finding from running orchestrator-worker patterns across our pipeline. Most teams hit this ceiling sooner than they expect.

Are open-source agents safe to run in production?

Depends on the isolation model. OpenClaw in a sandboxed configuration is operationally similar to running any third-party binary; in a non-sandboxed configuration, the security caveats are real and material. Self-hostable does not mean self-isolating. The OpenClaw review documents what we observed in both modes.

What is 'agentic' and is it different from 'autonomous'?

'Agentic' describes a property: the system can take actions toward a goal with some degree of decision-making latitude. 'Autonomous' describes a degree on that property: how much latitude. A workflow with one routing branch is mildly agentic and not autonomous. A loop that selects its own tools without human approval is highly agentic and approaching autonomous. The cornerstone definition lives on whatisanaiagent.com.

Where do I start if I have never built an agent?

Skip the frameworks. Write a single Python script that calls a model API, parses the response, and calls one tool. Read Anthropic's 'Building Effective Agents' paper. Then read our prompt-chaining essay. Then add a second tool. Build up to a routing pattern. Adopt a framework only when you outgrow the script. The Maturity Curve names the stages.

Did not find what you were looking for? See the glossary, the methodology page, or email oliver@digitalsignet.com.

Oliver Wakefield-Smith, Founder of Digital Signet
ABOUT THE AUTHOR
Oliver Wakefield-Smith
Founder, Digital Signet

Oliver runs Digital Signet, a research and product studio that operates ~500 production sites with AI agents as the engineering layer. The Digital Signet portfolio is built using a continuous AI-agent build pipeline, one of the largest agent-operated publishing operations on the open web. The handbook draws directly from those deployments: real cost data, real failure modes, real recovery patterns.