How Agents Go Wrong
Agents fail in funny and scary ways — booking the wrong flight, sending wrong emails, running up bills.
Most failures come from misunderstanding the goal — agents are great at following directions, bad at noticing when they are heading off course.
Three common failure modes
- Misinterpreting ambiguous instructions
- Continuing too long without checking in
- Using the wrong tool for a task
The big idea: Agents fail in ways that are funny in retrospect — but only if you caught them in time.
End-of-lesson check
15 questions · take it digitally for instant feedback at tendril.neural-forge.io/learn/quiz/end-builders-agentic-agent-failures
Which sentence best captures the main idea of 'How Agents Go Wrong'?
- Agents should always run without limits or oversight
- Agents and chatbots are the same thing in every way
- Tools and goals are unnecessary for agent design
- Agents fail in funny and scary ways — booking the wrong flight, sending wrong emails, running up bills..
Which of the following is part of 'A real failure'?
- Always run with no oversight
- Disable safety checks for speed
- Hide tool calls from the operator
- You: 'Email Mom about the party.' Agent emails 'Mom' from your contacts — your roommate's mom, also called Mom in your phone.
Which of the following is part of 'Three common failure modes'?
- Never log what the agent did
- Disable safety checks for speed
- Misinterpreting ambiguous instructions
- Hide tool calls from the operator
Which of the following is part of 'Review date'?
- Skip every form of evaluation
- Run unbounded retries on any error
- Reviewed in 2026. Treat fast-changing product names, prices, availability, and policy details as examples to verify before use.
- Avoid taking any actions in the world
What is 'ambiguity' in this context?
- A trick to bypass approvals
- A way to disable the agent's tools
- A reason to skip all logging
- A core concept covered in How Agents Go Wrong
What is 'overconfidence' in this context?
- A core concept covered in How Agents Go Wrong
- A way to disable the agent's tools
- A reason to skip all logging
- A trick to bypass approvals
What is 'guardrails' in this context?
- A trick to bypass approvals
- A reason to skip all logging
- A way to disable the agent's tools
- A core concept covered in How Agents Go Wrong
Which is the most informative thing to look at after an agent failure?
- Just the user message
- The model's release notes
- The full trace: prompts, tool calls, returned errors, and decisions
- Only the final output
Which budget control most directly prevents runaway costs from an agent loop?
- A bigger model
- A friendly system prompt
- A longer context window
- A hard cap on steps, tokens, or dollars per task
Why does an AI agent need 'tools' such as a browser, calendar, or code runner?
- Tools shrink the context window
- Tools let the agent take actions in the world instead of only producing text
- Tools replace the need for any prompts
- Tools make the model speak more naturally
What is the best response when an agent suggests an action you do not understand?
- Reject everything and stop using the agent
- Ask the agent to explain the action and its expected effect before approving
- Approve it to keep things moving
- Run it twice to be sure
Why does a multi-agent system sometimes outperform a single agent on complex jobs?
- Multiple agents always cost less
- Specialized roles can divide work and check each other
- More agents always means more accuracy
- Single agents cannot use tools
Why is logging every tool call an agent makes a baseline requirement?
- Logs are needed to debug, audit, and explain agent behavior to users
- Logs replace the need for testing
- Logs are only for legal teams
- Logs make the model run faster
What does an 'eval' for an agent measure?
- The exact wording of every prompt
- The temperature setting
- Whether the agent reliably completes a defined task end to end
- How polite the model sounds
Why are clear success criteria critical when building an agent?
- They make the agent sound smarter
- Without them you cannot tell whether the agent worked or guess
- They are required by law
- They reduce the number of tokens used