What are the steps involved in implementing a circuit breaker pattern in a Python-based microservices architecture to improve fault tolerance and resilience?

Implementing a circuit breaker pattern in a Python microservices architecture involves several steps.

1. First, identify dependencies that might potentially fail.
2. Next, integrate a circuit breaker library or create a custom one to monitor these dependencies. Of course, remember to set thresholds for failure rates and response times.
3. When a dependency exceeds these thresholds, the circuit breaker opens, preventing further requests and signaling a failure.
4. During this state, you can apply fallback mechanisms or return cached data.
5. After a predefined time, the circuit breaker transitions to a half-open state, allowing some requests to test if the dependency has recovered.

Keep in mind that successful requests close the circuit.