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Beyond numeric scores, you can annotate traces with tags, comments, expected values, and metadata to provide context and build better datasets. These annotations flow between logs, datasets, and experiments.

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Apply tags

Tags categorize and organize traces across your project. Use tags to mark traces for review, indicate status, or group related examples. Tags flow between logs, datasets, and experiments.

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Configure tags

Set up tags at the project level:
  1. Navigate to the Configuration tab in your project.
  2. Add, modify, or delete tags with custom names, colors, and descriptions. Configure tags

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Add tags

Select traces and apply tags from the table or trace view:

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Add comments

Comments provide free-form context and explanations. Use comments to explain why a trace succeeded or failed, note patterns or edge cases, share insights with teammates, or document corrections.
Open any trace and add comments in the trace view:Copy links to comments to share with teammates. Comments are searchable using the filter menu.

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Update expected values

Expected values define the correct or ideal output for a given input. Update expected values to provide ground truth for evaluation, document user corrections, specify multiple acceptable answers, or label categorical data.
Click any expected field in a trace to edit it directly. You can:
  • Enter structured JSON data
  • Use form-based editing (if schemas are defined)
  • Write categorical labels via human review scores
  • Copy expected values from other spans Write to expected

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Add metadata

Metadata provides structured context for filtering and analysis. Common metadata includes user IDs and session IDs, feature flags or A/B test variants, geographic or demographic information, request source or client type, and custom business context.
Add metadata when logging or via feedback:
// When logging
span.log({
  input,
  output: result,
  metadata: {
    user_id: userId,
    feature_variant: "test-a",
    request_source: "mobile-app",
  },
});

// Via feedback
logger.logFeedback({
  id: spanId,
  metadata: {
    reviewer: "[email protected]",
    review_date: new Date().toISOString(),
    category: "edge-case",
  },
});

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Filter by annotations

Use filters to find annotated traces: 
WHERE tags INCLUDES "needs-review"

WHERE comment IS NOT NULL

WHERE metadata.category = "edge-case"

WHERE expected IS NOT NULL
Combine filters to build precise queries for dataset curation.

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Next steps