
The Guardian: Monitoring Agent Execution
Shed light on the black box. Learn how to use Bedrock Traces, CloudWatch, and X-Ray to monitor the complex reasoning and tool-calling behavior of your agents.
Seeing the Invisible
The greatest risk with autonomous agents is that they operate in a "Black Box." If an agent spends $10 invoking tools in an infinite loop without ever answering the user, how would you know? If it makes a decision based on a hallucinated observation, how would you debug it?
In the AWS Certified Generative AI Developer – Professional exam, you must demonstrate mastery of Agent Observability. You need to be able to "look inside the mind" of the agent while it is working.
1. The Bedrock Trace ID
When you interact with an Amazon Bedrock Agent, you can enable the Trace feature. A Trace provides a step-by-step log of the agent's internal reasoning.
The Trace Categories:
- Pre-processing: Did the agent understand the user's intent?
- Orchestration: The actual ReAct loop (Thought -> Action -> Observation).
- Post-processing: How the agent formatted the final answer.
Pro Developer Strategy: Always enable enable_trace=True in your development environment to catch "Logic Regressions" early.
2. Using CloudWatch for Agent Monitoring
Every time a Bedrock Agent calls a Lambda function (Action Group), those logs are sent to Amazon CloudWatch.
What to monitor:
- Lambda Latency: Is your tool taking more than 5 seconds? (Likely to cause an agent timeout).
- Error Rates: Are your Action Groups returning 500 errors?
- Usage Metrics: Tracking the number of tokens consumed per agent session to identify "Runaway Agents."
3. Distributed Tracing with AWS X-Ray
An agent call often involves a complex chain:
User -> API Gateway -> Lambda -> Bedrock Agent -> Lambda (Tool) -> DynamoDB.
AWS X-Ray allows you to see this entire "Service Map." It helps you identify exactly which link in the chain is slow or failing. If the agent is "hanging," X-Ray will show you if it's waiting on the Model or waiting on the Tool's database call.
graph LR
U[User] -->|Trace ID| API[API Gateway]
API -->|Trace ID| L1[Lambda: Router]
L1 -->|Trace ID| BA[Bedrock Agent]
BA -->|Trace ID| L2[Lambda: Tool]
L2 -->|Trace ID| DB[(DynamoDB)]
style BA fill:#ff9900,color:#fff
4. Detecting the "Agent Death Spiral"
An "Agent Death Spiral" is an infinite loop where the agent calls a tool, gets an error, and tries the same tool over and over again.
How to Monitor:
- Set a CloudWatch Alarm on the "Invocations" metric for your Action Group Lambda.
- If the count exceeds 5 invocations within a single session (detected via a custom log filter), trigger an SNS Notification to an engineer.
5. Cost Observability
A Professional Developer treats cost as a performance metric.
- Use AWS Cost Explorer with the
AgentIDtag. - Implement Throttling on the user side if their session token usage exceeds a specific USD threshold.
6. Code Example: Inspecting a Bedrock Trace
import boto3
client = boto3.client('bedrock-agent-runtime')
def invoke_with_trace(prompt, agent_id, agent_alias_id):
response = client.invoke_agent(
agentId=agent_id,
agentAliasId=agent_alias_id,
sessionId='test-session-001',
inputText=prompt,
enableTrace=True # CRITICAL FOR MONITORING
)
# Trace information is streamed back in the response
for event in response.get('completion'):
if 'trace' in event:
trace = event['trace']['trace']
if 'orchestrationTrace' in trace:
print("Model Thought:", trace['orchestrationTrace'].get('modelInvocationInput', ''))
print("Action Taken:", trace['orchestrationTrace'].get('invocationInput', ''))
Knowledge Check: Test Your Monitoring Knowledge
?Knowledge Check
A developer's AI agent is correctly answering most questions, but occasionally it takes 60 seconds to respond and then fails. What is the most effective way to identify exactly where the delay is occurring in the agentic workflow?
Summary
Observability is the difference between a "Demo" and a "Product." By mastering Traces, CloudWatch, and cost-tagging, you ensure your agents are reliable and efficient.
This concludes Domain 2: Implementation and Integration. You have completed more than 50% of the course! In the next module, we move to Domain 3: AI Safety, Security, and Governance.
Next Module: The Zero Trust Foundation: IAM Best Practices for GenAI