MT5 Log Reader

Read MetaTrader 5 log files directly to access Print() output from indicators, scripts, and expert advisors without requiring manual Experts pane inspection.

Self-Evolving Skill: This skill improves through use. If instructions are wrong, parameters drifted, or a workaround was needed — fix this file immediately, don't defer. Only update for real, reproducible issues.

Purpose

Implement "Option 3" dual logging pattern:

• Print() - MT5 log files (human-readable via Experts pane)
• CSV files - Structured data (programmatic analysis)

Claude Code can autonomously read both outputs without user intervention.

When to Use This Skill

Use this skill when:

• Validating MT5 indicator/script execution
• Checking compilation or runtime errors
• Analyzing Print() debug output
• Verifying unit test results (Test_PatternDetector, Test_ArrowManager)
• User mentions checking "Experts pane" manually

Log File Location

MT5 logs are stored at:

$MQL5_ROOT/Program Files/MetaTrader 5/MQL5/Logs/YYYYMMDD.log

File Format:

• Encoding: UTF-16LE (Little Endian)
• Structure: Tab-separated fields (timestamp, source, message)
• Size: Grows throughout day (typically 10-100KB)

Instructions

1. Construct today's log path

/usr/bin/env bash << 'SKILL_SCRIPT_EOF'
# Determine current date
TODAY=$(date +"%Y%m%d")

# Build absolute path
LOG_FILE="$MQL5_ROOT/Program Files/MetaTrader 5/MQL5/Logs/${TODAY}.log"
SKILL_SCRIPT_EOF

2. Read the entire log file

Use Read tool:

• File path: Absolute path from step 1
• The file contains all Print() statements from MT5 indicators/scripts
• UTF-16LE encoding is automatically handled by Read tool

3. Search for specific content (optional)

Use Grep to filter entries:

Pattern: indicator name, "error", "test.*passed", etc.
Path: Log file path from step 1
Output mode: "content" with -n (line numbers)
Context: -A 5 for 5 lines after matches

4. Analyze recent entries (optional)

Use Bash with tail for latest output:

tail -n 50 "$LOG_FILE"

Common Validation Patterns

Check unit test results

Search for test pass/fail indicators:

Pattern: test.*passed|test.*failed|Tests Passed|Tests Failed|ALL TESTS PASSED
Output mode: content
Context: -B 2 -A 2

Find compilation errors

Pattern: error|ERROR|warning|WARNING|failed to create
Output mode: content
Context: -A 3

Monitor specific indicator

Pattern: CCI Rising Test|PatternDetector|ArrowManager
Output mode: content
Context: -A 2

View initialization messages

Pattern: OnInit|initialization|Initialization complete|Phase \d+
Output mode: content

Examples

Example 1: Validate unit test completion

Input: User compiled Test_PatternDetector.mq5
Action:
  1. Read today's log file
  2. Grep for "Test.*PatternDetector|Tests Passed|Tests Failed"
  3. Report results (e.g., "17 tests passed, 0 failed")
Output: Test status without user checking Experts pane

Example 2: Check for runtime errors

Input: User reports indicator not working
Action:
  1. Read today's log file
  2. Grep for "ERROR|error|failed" with -A 3 context
  3. Analyze error messages
Output: Specific error details and line numbers

Example 3: Verify Phase 2 arrow creation

Input: User asks "did the test arrow get created?"
Action:
  1. Read today's log file
  2. Grep for "Phase 2|Test arrow created|Failed to create"
  3. Check for success/failure messages
Output: Arrow creation status with timestamp

Security Considerations

• Log files may contain sensitive trading data (symbol names, account info)
• Restricted to Read, Bash, Grep tools only (no network access via WebFetch)
• Do not expose absolute paths unnecessarily in user-facing output
• Filter sensitive information when reporting results
• No file modification operations allowed

Integration with Dual Logging

This skill enables programmatic access to one half of the dual logging pattern:

1. MT5 Log Files (this skill) - Human-readable Print() output
2. CSV Files (CSVLogger.mqh) - Structured audit trails for validation

Both are accessible without user intervention:

• MT5 logs: Read via this skill
• CSV files: Read directly via Read tool or validate_export.py

Validation Checklist

When using this skill:

• Log file exists for today's date
• File size > 0 (not empty)
• Contains expected indicator/script output
• Timestamps match execution time
• Error messages (if any) are actionable
• Test results (if applicable) show pass/fail counts

References

• MT5 file locations: docs/guides/MT5_FILE_LOCATIONS.md
• Dual logging implementation: docs/plans/cci-rising-pattern-marker.yaml Phase 3-4
• CSVLogger library: Program Files/MetaTrader 5/MQL5/Indicators/Custom/Development/CCINeutrality/lib/CSVLogger.mqh

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Troubleshooting

Issue	Cause	Solution
Log file not found	Wrong date or path	Verify YYYYMMDD.log format and MQL5_ROOT env var
Empty log file	MT5 not running or no output	Ensure MT5 is running and Print() is being called
Encoding errors	UTF-16LE not handled	Read tool handles encoding automatically
Missing test results	Test not executed	Compile and run test script in MT5 first
Grep finds nothing	Wrong pattern	Use case-insensitive (-i) or broader pattern
Old log data	Log rotation	Each day creates new YYYYMMDD.log file
Path contains spaces	Unquoted path variable	Quote paths: "$LOG_FILE"
Sensitive data exposed	Trading info in logs	Filter sensitive fields when reporting to user

Post-Execution Reflection

After this skill completes, check before closing:

1. Did the command succeed? — If not, fix the instruction or error table that caused the failure.
2. Did parameters or output change? — If the underlying tool's interface drifted, update Usage examples and Parameters table to match.
3. Was a workaround needed? — If you had to improvise (different flags, extra steps), update this SKILL.md so the next invocation doesn't need the same workaround.

Only update if the issue is real and reproducible — not speculative.