What a single agent gives you

The defining characteristics of a single agent, from "Single vs Multi-Agent System?":

• Sequential: it does step A, then step B, in order.
• Unified context: it keeps one continuous history of the whole conversation. Every new step sees all previous steps, thoughts, and tool outputs.
• Stateful: early decisions directly inform later actions with no need to pass messages between separate components.

The strengths that follow from this are about reliability:

• Context continuity: no information is lost between steps, because it all lives in one place.
• Simplicity: it is easier to debug, test, and maintain.
• Transparency: there is one clear execution path and decision trail.

The weaknesses are about scale and speed:

• Sequential bottlenecks: it is slow for work that could have been done in parallel.
• Context window limits: a long task will eventually overflow the useful context window, leading to errors and forgotten details (this is closely related to context rot).
• Inefficiency: it can waste tokens repeating context, and it is limited to one model's capabilities.