Common Agent Failure Patterns
2 min read
Most early agent failures come from the environment around the model. Teams add context, tools, and freedom to make an agent more capable, then discover that each addition creates another decision the agent can get wrong.
The practical design instinct is subtraction. Give the agent the smallest set of information, actions, and choices that can complete the task.
More can reduce capability
Section titled “More can reduce capability”More tools make selection harder and consume context even when unused. More context buries the relevant signal and degrades recall as the window fills. More freedom expands the search space until the agent stalls or chooses an arbitrary direction.
A focused agent with five relevant tools, dense context, and explicit constraints will often outperform one with fifty tools and an entire wiki in its prompt. Capability depends on usable signal, not the volume of material available.
Seven recurring mistakes
Section titled “Seven recurring mistakes”- Unstructured context. Pasting everything into the prompt makes relevance the agent’s problem. Context must be curated, not accumulated.
- Unverified output. Agents declare success early and can misread their own results. Verification must test the artifact independently.
- Tool flooding. Every tool adds tokens and another routing choice. Expose only the capabilities required for the current role.
- Vague instructions. “Make it better” permits many incompatible interpretations. Name the outcome and the acceptance criteria.
- Inconsistent structure. Agents use format as a signal. Stable instruction and output structures produce more stable behaviour.
- Excessive freedom. Unbounded option spaces create hesitation and arbitrary choices. Constraints make autonomy usable.
- Missing requirements. Asking the agent to rediscover known requirements increases cost and failure risk. State what the system already knows.
These failures reinforce one rule: improve the complete environment before escalating the model. With the agent’s components and their interactions established, the next chapter puts them into motion through the agent loop.