Agent Observability Logger

NotificationIntermediateHook Type: notification

Agent Observability Logger captures every tool invocation, notification, and session event into a structured JSONL log file. Each entry includes the timestamp, tool name, input summary, output status, and token usage. This creates a complete audit trail that helps you understand what Claude did during a session, debug unexpected behavior, track patterns over time, and satisfy compliance requirements. Logs rotate daily and can be forwarded to any observability platform.

loggingauditobservabilitydebuggingcompliance

Hook Code

#!/bin/bash
# Agent Observability Logger Hook
# Logs all Claude Code actions to structured JSONL

LOG_DIR="${HOME}/.claude/logs"
LOG_FILE="$LOG_DIR/agent-$(date +%Y-%m-%d).jsonl"

mkdir -p "$LOG_DIR"

TIMESTAMP=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
SESSION_ID="${CLAUDE_SESSION_ID:-unknown}"

# Build structured log entry
LOG_ENTRY=$(jq -n   --arg ts "$TIMESTAMP"   --arg session "$SESSION_ID"   --arg tool "$TOOL_NAME"   --arg event "$EVENT_TYPE"   --arg input "$TOOL_INPUT"   --arg output "$TOOL_OUTPUT"   '{
    timestamp: $ts,
    session_id: $session,
    tool: $tool,
    event: $event,
    input_preview: ($input | if length > 200 then .[:200] + "..." else . end),
    output_preview: ($output | if length > 200 then .[:200] + "..." else . end)
  }')

echo "$LOG_ENTRY" >> "$LOG_FILE"

# Rotate logs older than 30 days
find "$LOG_DIR" -name "agent-*.jsonl" -mtime +30 -delete 2>/dev/null

exit 0

Add this hook to your Claude Code settings or .claude/settings.json to activate.

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Agent Observability Logger

About Agent Observability Logger

Claude Code hooks let you run custom shell commands automatically in response to specific events during Claude's operation. Agent Observability Logger is a Notification hook at the Intermediate level that automates tasks at key moments in your development workflow, reducing manual steps and enforcing consistency across your team.

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