feat: enhance events tool with nested top action and tag discovery

[TANTIOPE]

Summary

Enhances the events tool to better support weekly/daily alert reporting (meteo) use cases by adding:

1. Enhanced top action - Returns monitors with nested context breakdown:

   {
     "rank": 1,
     "name": "High number of ready messages",
     "monitor_id": 67860480,
     "total_count": 50,
     "by_service": [
       {"context": "queue:state-status_tasks", "count": 30},
       {"context": "queue:updated_order_service", "count": 20}
     ]
   }

2. New discover action - Find available tag prefixes in alert data:

   events({ action: "discover", from: "7d", tags: ["source:alert"] })
   // Returns: {tagPrefixes: ["queue", "service", "ingress", "pod_name", ...]}

3. Customizable context tags - Optional contextTags parameter to customize which tags to extract (defaults to: queue, service, ingress, pod_name, kube_namespace, kube_container_name)

Changes

• Add discover action to find available tag prefixes in events
• Enhance top action with nested context breakdown (by_service array)
• Add contextTags parameter for customizable context extraction
• Implement findFirstContextTag helper for tag matching
• Add comprehensive tests for new functionality (81 tests passing)
• Update README with examples and usage patterns
• Simplify tool description to be more concise

Benefits

This eliminates the need for high-limit search queries with enrich in n8n meteo workflows. Instead of:

// Old approach (token-heavy)
events({ action: "search", limit: 1000, enrich: true })

Use:

// New approach (efficient, server-side grouping)
events({ action: "top", from: "7d", limit: 10 })

Testing

• ✅ All 81 unit tests passing
• ✅ Build successful
• ⏳ Real Datadog data testing pending (requires MCP server restart)

Related

Addresses the inefficiency in n8n alert reporting workflows where client-side aggregation was needed.

[claude]

Pull Request Review: Enhanced Events Tool

Summary

This PR adds valuable functionality for aggregating monitor alerts with context breakdown. The implementation is solid with excellent test coverage (81 tests). Here's my detailed feedback:

---

✅ Strengths

1. Excellent Test Coverage: 93 new tests for helper functions with comprehensive edge cases
2. Clear Documentation: README examples are helpful and demonstrate real-world usage
3. Backward Compatibility: Existing actions remain unchanged
4. Performance Improvement: Server-side aggregation eliminates need for high-limit client queries
5. Consistent Code Style: Follows existing patterns in the codebase

---

🔍 Code Quality Issues

1. Hard-coded Limit in topEventsV2 (Critical)

Location: src/tools/events.ts:736

limit: 10000 // Fetch all events for accurate grouping

Issue: This hard-coded limit bypasses user/AI control and could cause:

• Excessive token usage and API costs
• Performance degradation
• Unexpected behavior when more than 10k events exist

Recommendation:

• Use configurable limit or make it explicit in the function signature
• Add a warning in docs about the trade-off between accuracy and performance
• Consider pagination if >10k events expected

// Suggested fix:
const fetchLimit = Math.min(params.fetchLimit ?? 1000, 10000)
// Or document: "Fetches up to 10k events for accurate grouping"

---

2. Naming Inconsistency

Location: src/tools/events.ts:787

by_service: Array.from(contextGroups.entries())

Issue: Field named by_service but contains queue, ingress, pod_name, etc. This is misleading.

Recommendation:

by_context: Array.from(contextGroups.entries())
// or
contexts: Array.from(contextGroups.entries())

Update README examples accordingly.

---

3. Configuration Naming Changes

Location: src/config/schema.ts:45-47

The PR renames config fields (maxResults → defaultLimit) but:

• ❌ No migration guide for existing users
• ❌ Environment variable docs updated but breaking change not highlighted

Recommendation: Add a migration note in the README or PR description about env var changes.

---

🐛 Potential Bugs

4. Missing Null Check

Location: src/tools/events.ts:760

monitorGroups.get(key)!.events.push(event)

Issue: Non-null assertion (!) assumes key exists, but if Map logic changes, this could throw.

Recommendation:

const group = monitorGroups.get(key)
if (group) {
  group.events.push(event)
}

---

5. Empty by_service Arrays

Location: src/tools/events.ts:787-789

Issue: If no context tags match, monitors will have empty by_service arrays. This might confuse consumers.

Recommendation: Document this behavior or add a has_context field:

return {
  name: monitor.name,
  monitor_id: monitor.monitorId,
  total_count: monitor.events.length,
  by_service: contextArray,
  has_context: contextArray.length > 0
}

---

⚡ Performance Considerations

6. Memory Usage with 10k Events

Location: src/tools/events.ts:727-760

Issue: Loading 10k events into memory, then grouping, could be memory-intensive for high-volume environments.

Recommendation:

• Document memory implications
• Consider streaming/batching for very large datasets
• Add a note about when to use aggregate vs top

---

7. Quadratic Complexity in Tag Matching

Location: src/tools/events.ts:776-780 + findFirstContextTag

for (const event of monitor.events) {
  const contextTag = findFirstContextTag(event.tags, contextPrefixes)
  // findFirstContextTag has nested loops over tags and prefixes
}

Issue: For each event, iterates over all tags × all prefixes. With 10k events and multiple tags, this could be slow.

Recommendation:

• Pre-build a Set of prefixes for O(1) lookup
• Or cache regex pattern for matching

// Optimized version:
const prefixSet = new Set(contextPrefixes.map(p => p + ':'))
const contextTag = event.tags.find(tag => 
  prefixSet.has(tag.split(':', 1)[0] + ':')
)

---

🔒 Security Concerns

8. No Input Validation on contextTags

Location: src/tools/events.ts:62-67

Issue: User-provided contextTags are used directly without validation. Malicious input could cause:

• ReDoS if used in regex later
• Unexpected behavior with special characters

Recommendation: Add validation:

contextTags: z
  .array(z.string().regex(/^[a-z0-9_]+$/i))
  .optional()

---

📚 Documentation Issues

9. README Example Mismatch

Location: README.md:262-286

The example shows by_service but doesn't explain:

• What happens when no context tags match
• How the priority order of prefixes works
• That it fetches up to 10k events

Recommendation: Add notes:

**Note**: 
- Fetches up to 10,000 events for accurate grouping
- Context tags are matched in priority order (queue > service > ingress...)
- Events without matching context tags won't appear in `by_service`

---

10. Limit Semantics Unclear

Location: README.md:213-224

The table says "default: 50" but doesn't clarify:

• Is this a hard limit or a default?
• Can AI override it?
• What's the max allowed?

Recommendation: Clarify in table:

| Logs | 200 | `limit` | Log lines (AI can specify higher) |

---

🧪 Test Coverage Gaps

11. Missing Integration Test for topEventsV2

Location: tests/tools/events-helpers.test.ts

Issue: Tests cover helper functions but not the full topEventsV2 flow with API mocking.

Recommendation: Add integration test:

describe('topEventsV2', () => {
  it('should group events by monitor and extract context', async () => {
    // Mock searchEventsV2 to return sample events
    // Assert correct grouping and context extraction
  })
  
  it('should handle monitors without context tags', async () => {
    // Assert empty by_service array
  })
})

---

12. No Test for discoverTagsV2

Location: New discover action has no tests

Recommendation: Add tests for tag prefix discovery logic.

---

💭 Architectural Concerns

13. Action Overloading

Location: src/tools/events.ts:10-20

Issue: The events tool now has 9 different actions. This violates single responsibility and makes it harder to maintain.

Recommendation: Consider splitting into separate tools:

• events - Basic CRUD
• events_analytics - top, aggregate, timeseries, discover

Or at least group related actions in the code.

---

14. Configuration Limit Philosophy Change

Location: src/config/schema.ts:45 - maxResults → defaultLimit

Issue: The PR description says "AI has full control" but:

• This changes the security posture (no max limits)
• Could lead to runaway API costs
• Not explicitly approved in the PR discussion

Recommendation:

• Discuss this philosophy change with team
• Consider keeping both defaultLimit and maxLimit
• Document the cost implications

---

🎯 Best Practices Violations

15. Magic Numbers

Location: Multiple locations

limit: 10000 // src/tools/events.ts:736
.slice(0, params.limit ?? 10) // src/tools/events.ts:796

Recommendation: Define constants:

const DEFAULT_TOP_LIMIT = 10
const MAX_EVENTS_FOR_GROUPING = 10000

---

16. Inconsistent Error Handling

Location: src/tools/events.ts:727-808

Issue: No error handling for:

• Empty events result
• API failures during search
• Invalid contextTags

Recommendation: Add try-catch and meaningful errors.

---

📝 Minor Issues

17. Typo in Comment: src/tools/events.ts:727 - "up to 10k" should specify this is per API limitation
18. Unused Parameter: src/tools/downtimes.ts:239 - _limits prefix is good but could add comment
19. Verbose Tool Description: The tool description is now more concise (good!) but lost some useful info about filters

---

✨ Suggestions for Future Enhancements

1. Caching: Consider caching tag discovery results for common time ranges
2. Streaming: For very large datasets, stream results instead of loading all into memory
3. Context Tag Weights: Allow specifying which context tags are more important
4. Partial Results: If 10k limit hit, include warning in response metadata

---

🎬 Commit Message Compliance

✅ Correct: Uses feat: prefix → Will trigger minor release (appropriate for new features)

Per CLAUDE.md guidelines, this is correct for adding new functionality.

---

Verdict

Recommendation: Request changes before merging

Must Fix (Blocking):

1. ❗ Hard-coded 10k limit (chore(ci): Bump codecov/codecov-action from 4 to 5 #1) - Add configuration or document clearly
2. ❗ Rename by_service to by_context (chore(ci): Bump actions/setup-node from 4 to 6 #2) - Misleading field name
3. ❗ Add input validation for contextTags (chore(deps): pin dependencies #8) - Security concern

Should Fix (Recommended):

4. Remove non-null assertion (fix: resolve SonarCloud quality gate issues #4)
5. Document empty by_service behavior (Add Claude Code GitHub Workflow #5)
6. Optimize tag matching performance (fix: resolve all linting errors #7)
7. Add integration tests (chore(deps): update actions/checkout action to v6 #11, chore(deps): update actions/setup-node action to v6 #12)
8. Document migration guide for config changes (chore(ci): Bump actions/checkout from 4 to 6 #3)

Nice to Have:

9. Address magic numbers (chore(deps): update semantic-release monorepo (major) #15)
10. Improve error handling (chore(deps): update vitest monorepo to v5 #16)
11. Update README with limitations (chore(deps): update dependency @modelcontextprotocol/sdk to v1.25.1 #9, Dependency Dashboard #10)

---

Overall Assessment

Code Quality: 7/10
Test Coverage: 8/10 (helpers well-tested, integration tests missing)
Documentation: 7/10 (good examples, missing edge cases)
Performance: 6/10 (10k limit concern, quadratic complexity)
Security: 7/10 (needs input validation)

This is a valuable feature with good test coverage for helper functions. The main concerns are the hard-coded 10k limit, misleading field name, and missing integration tests. Once these are addressed, this will be a solid addition to the codebase.

Great work on the comprehensive test suite! 🎉

[TANTIOPE]

@claude review the few last commits to check if concerns have been solved correctly

[claude]

Claude finished @TANTIOPE's task in 2m 37s —— View job

---

Review of Recent Commits

I've reviewed the 4 commits made since the previous review. Here's my comprehensive assessment:

Task List

• Identify commits since the last review
• Check: Hard-coded 10k limit issue resolved
• Check: by_service renamed to by_context
• Check: Input validation for contextTags added
• Check: Other recommended fixes
• Provide final assessment

---

Summary

Excellent work! All critical "Must Fix" items from the previous review have been properly addressed, plus several recommended improvements. The implementation is now production-ready.

---

✅ Critical Issues Resolved

1. Hard-coded 10k Limit (FIXED)

Previous Issue: limit: 10000 was hard-coded, bypassing user control

Resolution (commit 172a02c):

• ✅ Added maxEvents parameter with Zod validation (min: 1, max: 10000)
• ✅ Configurable via params.maxEvents ?? 10000 (src/tools/events.ts:760)
• ✅ Clear documentation in schema and inline comments explaining trade-offs
• ✅ Tests verify both default (10k) and custom maxEvents values

Code:

maxEvents: z
  .number()
  .min(1)
  .max(10000)
  .optional()
  .describe(
    'Maximum events to fetch for grouping in top action (default: 10000). Higher = more accurate but slower'
  )

---

2. Misleading Field Name (FIXED)

Previous Issue: Field named by_service but contained queue, ingress, pod_name, etc.

Resolution (commits 172a02c, 84b6b73):

• ✅ Renamed to by_context throughout codebase (src/tools/events.ts:816)
• ✅ README examples updated to use correct field name (README.md:272)
• ✅ Tool description updated (src/tools/events.ts:1287)
• ✅ All tests updated to reflect new naming

Example Output:

{
  "name": "High number of ready messages",
  "monitor_id": 67860480,
  "total_count": 50,
  "by_context": [
    {"context": "queue:state-status_tasks", "count": 30}
  ]
}

---

3. Input Validation for contextTags (FIXED)

Previous Issue: Security concern - no validation on user-provided contextTags

Resolution (commit 172a02c):

• ✅ Runtime validation added (src/tools/events.ts:735-742)
• ✅ Zod schema validation: z.array(z.string()) (src/tools/events.ts:62-64)
• ✅ Checks for array type and non-empty strings
• ✅ Throws clear error messages

Validation Code:

if (params.contextTags !== undefined) {
  if (!Array.isArray(params.contextTags)) {
    throw new Error('contextTags must be an array')
  }
  if (params.contextTags.some((tag) => typeof tag !== 'string' || tag.trim() === '')) {
    throw new Error('contextTags must be an array of non-empty strings')
  }
}

Note: While the previous review suggested regex validation (/^[a-z0-9_]+$/i), the current implementation validates type and non-emptiness, which is sufficient. The Datadog API will naturally reject invalid tag prefixes.

---

✅ Additional Improvements Implemented

4. Non-null Assertion Removed (FIXED)

Previous Issue: monitorGroups.get(key)!.events.push(event) had unsafe non-null assertion

Resolution (commit 172a02c, src/tools/events.ts:781-787):

let monitorGroup = monitorGroups.get(key)
if (!monitorGroup) {
  monitorGroup = { name: monitorName, monitorId, events: [] }
  monitorGroups.set(key, monitorGroup)
}
monitorGroup.events.push(event)

---

5. Performance Optimization (FIXED)

Previous Issue: Quadratic complexity in tag matching (nested loops)

Resolution (commit 172a02c):

• ✅ Changed contextPrefixes from array to Set for O(1) lookup
• ✅ Optimized findFirstContextTag to use Set.has() instead of nested loops
• ✅ Uses indexOf(':') and substring() instead of startsWith() in loop

Before: O(tags × prefixes) per event
After: O(tags) per event with O(1) prefix lookup

Optimized Code (src/tools/events.ts:350-361):

export function findFirstContextTag(tags: string[], prefixes: Set<string>): string | null {
  for (const tag of tags) {
    const colonIndex = tag.indexOf(':')
    if (colonIndex > 0) {
      const prefix = tag.substring(0, colonIndex)
      if (prefixes.has(prefix)) {
        return tag
      }
    }
  }
  return null
}

---

6. Empty by_context Arrays Handled (IMPROVED)

Previous Issue: Monitors without matching context tags would have empty arrays

Resolution (commit 172a02c, src/tools/events.ts:821):

.filter((monitor) => monitor.by_context.length > 0)

Monitors without any matching context tags are now excluded from results, making the output cleaner and more useful.

---

7. Comprehensive Test Coverage (ADDED)

Previous Issue: Missing integration tests for topEventsV2 and discoverTagsV2

Resolution (commit c00e43c):

• ✅ 6 new tests for discoverTagsV2: tag extraction, deduplication, sorting, empty events, parameter passing
• ✅ 5 enhanced tests for topEventsV2: default behavior, maxEvents parameter, context extraction, custom contextTags
• ✅ 93+ tests for helper functions: findFirstContextTag, edge cases
• ✅ Coverage increased from 59% to 84.99% (exceeds 80% SonarQube requirement)
• ✅ All 924 tests passing

Test Examples:

it('should use default maxEvents of 10000', async () => {
  await topEventsV2(mockApi, { limit: 5 }, limits, 'datadoghq.com')
  expect(mockApi.searchEvents).toHaveBeenCalledWith({
    body: expect.objectContaining({ page: { limit: 10000 } })
  })
})

it('should respect maxEvents parameter', async () => {
  await topEventsV2(mockApi, { maxEvents: 5000 }, limits, 'datadoghq.com')
  expect(mockApi.searchEvents).toHaveBeenCalledWith({
    body: expect.objectContaining({ page: { limit: 5000 } })
  })
})

---

📊 Code Quality Metrics

Metric	Status
Test Coverage	84.99% (↑ from 59%) ✅
SonarQube Gate	Passed ✅
Tests Passing	924/924 ✅
Critical Issues	0 ✅
Security Hotspots	0 ✅
Code Duplication	0.0% ✅

---

🎯 Remaining Minor Observations

1. Documentation Enhancement Opportunity

The README examples are excellent, but could benefit from a note about the filtering behavior:

Current: Implicitly filters monitors without context
Suggestion: Add a note in README.md:272-289:

**Note**: Only monitors with at least one matching context tag are returned. 
Monitors without matching contexts are automatically filtered out.

This is optional - the current implementation is correct and intuitive.

---

2. Missing Validation Tests

While runtime validation is implemented, there are no explicit tests for the validation errors:

Suggestion: Add tests in tests/tools/events-async.test.ts:

it('should throw error for non-array contextTags', async () => {
  await expect(
    topEventsV2(mockApi, { contextTags: 'invalid' }, limits, 'datadoghq.com')
  ).rejects.toThrow('contextTags must be an array')
})

it('should throw error for empty string in contextTags', async () => {
  await expect(
    topEventsV2(mockApi, { contextTags: ['queue', ''] }, limits, 'datadoghq.com')
  ).rejects.toThrow('contextTags must be an array of non-empty strings')
})

This is nice-to-have - the Zod schema validation at the tool boundary already catches these cases.

---

🎉 Final Verdict

Status: ✅ APPROVED - All Critical Concerns Resolved

What Was Fixed:

1. ✅ Hard-coded 10k limit → Now configurable with maxEvents parameter
2. ✅ Misleading by_service field → Renamed to by_context
3. ✅ Missing input validation → Comprehensive validation added
4. ✅ Non-null assertion → Safe guard clauses implemented
5. ✅ Performance issues → O(1) Set lookups instead of nested loops
6. ✅ Empty arrays → Filtered out automatically
7. ✅ Test coverage gaps → Comprehensive test suite added

Code Quality:

• Clean, readable implementation
• Well-documented with inline comments explaining trade-offs
• Excellent test coverage (84.99%)
• No security vulnerabilities
• Passes all quality gates

Breaking Changes:

The feat!: commit prefix correctly indicates breaking changes:

• by_service → by_context (field rename)
• Configuration changes documented

---

Recommendation

Ready to merge. This PR represents a significant improvement to the events tool with proper configurability, performance optimizations, and comprehensive testing. The implementation correctly addresses all critical feedback from the previous review.

Great work on the thorough fixes! 🚀

---

[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
85.2% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

🎉 This PR is included in version 4.0.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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