What is an Audit Trail?
An audit trail is a chronological, immutable record of every tool call, policy evaluation, and decision made by PolicyLayer — essential for compliance, debugging, and security forensics.
WHY IT MATTERS
When an AI agent operates autonomously, the question "what did it do?" becomes critical. Without an audit trail, agent actions are invisible — you cannot verify compliance, investigate incidents, or demonstrate governance to regulators. The audit trail is the record of truth for agent operations.
Audit trails serve three distinct audiences. Security teams use them to detect anomalies, investigate incidents, and verify that policies are enforced correctly. Compliance teams use them to demonstrate that agent operations meet regulatory requirements — SOC 2, GDPR, PCI DSS all require evidence of access controls and decision logging. Developers use them to debug agent behaviour, understand why a tool call was denied, and optimise policies based on real usage patterns.
The value of an audit trail is proportional to its completeness. A partial trail — one that only logs denials, or only logs certain servers — leaves gaps that undermine its utility. PolicyLayer logs every tool call that passes through it, regardless of the policy outcome. This creates a complete picture of agent activity that can be queried, analysed, and retained according to organisational requirements.
HOW POLICYLAYER USES THIS
PolicyLayer generates a structured audit trail for every tool call. Each entry includes: timestamp, MCP server name, tool name, arguments (optionally redacted for sensitive fields), matched policy rule, evaluation result (allow/deny/log), and any conditions that were checked. The audit trail is written to structured log output (JSON) and can be forwarded to any log aggregation system (ELK, Datadog, Splunk, CloudWatch). Retention and redaction policies are configurable to meet compliance requirements.