PII Scrubbing for AI Agent API Logs

PII scrubbing means redacting sensitive values before logs are stored, displayed, or uploaded. For AI agent API logs, that usually means removing API keys, bearer tokens, emails, phone numbers, card-like values, and token-like URL parameters.

Guardrly performs this scrubbing locally before any log data leaves your machine.

Local vs Cloud PII Scrubbing

Local PII scrubbing redacts sensitive values before logs are stored or uploaded. Cloud-only scrubbing removes data after it has already crossed the network, which means tokens, API keys, or customer identifiers may briefly exist in transit, server-side queues, or raw ingestion logs.

Approach	Where redaction happens	Main risk	Best fit
Local PII scrubbing	On the user's machine before upload	A local bug could miss a pattern	AI agent logs, API monitoring, production credentials
Cloud PII scrubbing	After data reaches the vendor cloud	Raw secrets may cross the network or enter queues	Low-sensitivity analytics with no tokens
Hybrid scrubbing	Local first, cloud validation second	More complexity	Regulated teams that want defense in depth

Guardrly uses local scrubbing so the cloud dashboard receives operation metadata, not raw secrets.

What Is PII Scrubbing?

PII scrubbing is the process of replacing sensitive values with safe placeholders. In AI agent monitoring, the goal is to preserve the operational signal, such as method, endpoint, platform, status code, latency, and risk level, while removing the values that could identify a customer or expose an account.

For example:

Raw value type	Scrubbed output
Authorization: Bearer sk_live_...	Authorization: [REDACTED]
customer@example.com	[email_redacted]
?access_token=abc123	?access_token=[REDACTED]
+1 415 555 0199	[phone_redacted]

What Gets Scrubbed

Authorization Headers

All Authorization header values are replaced with [REDACTED]. This includes Bearer tokens, API keys, and Basic auth credentials.

Access Tokens in URLs

URL parameters containing access_token, api_key, token, or key are replaced with [REDACTED].

Email Addresses

Email addresses in request bodies and URLs are replaced with [email_redacted].

Phone Numbers

Phone numbers (international and domestic formats) are replaced with [phone_redacted].

Credit Card Numbers

16-digit card numbers (with or without spaces or dashes) are replaced with [card_redacted].

What Is NOT Scrubbed

• Request URLs (endpoint paths are kept for monitoring purposes)
• HTTP method and status codes
• Response timing data
• Platform-specific non-sensitive fields

Technical Implementation

PII scrubbing runs on your local machine using 5 precompiled regex patterns. Processing time is under 1ms per request.

The scrubbed payload is what gets stored locally and uploaded to the cloud. The original sensitive data never leaves your machine.

Verification

You can verify scrubbing is working by checking your logs at app.guardrly.com/logs. Authorization headers and tokens should appear as [REDACTED].

Compliance

Guardrly's PII scrubbing approach supports compliance with:

• GDPR (data minimization principle)
• CCPA (personal information protection)
• SOC 2 (access control requirements)

For the broader MCP hardening checklist, read MCP server security best practices.