Metric Creation

Prerequisites

Before creating metrics, ensure you are on the correct workspace and branch. Use get_session_workspace_and_branch to check the current session context. For development work, create a branch with create_workspace_branch (the session switches automatically). See the model-exploration skill for the full workspace/branch tool reference.

Overview

A Honeydew metric is a named, reusable aggregation anchored to an entity. Unlike a calculated attribute (which is per-row), a metric collapses multiple rows into a single value. Metrics are context-sensitive: they automatically respond to whatever filters and groupings the consuming BI tool or analyst applies.

Your job is to build an aggregation function that users can later group by.

If a user asks for a group by ("sum sales by category"), ignore the group. You're building the aggregation to sum sales by ANYTHING. The user will later use it in a query with their chosen dimensions.

Use a metric when:

• The same aggregation logic is reused across dashboards, teams, or tools
• You need a governed, single source of truth for a KPI (e.g. "revenue", "active users")
• The calculation involves combining other metrics (ratios, deltas)

Do not use a metric when the value is per-row (use a calculated attribute instead).

Building the SQL Expression

Core Rules

• MUST use an aggregation function — metrics collapse rows
• DO NOT use window functions — only aggregations allowed
• DO NOT use joins or subqueries — simple expressions only
• NEVER use COUNT(*) — use the entity's built-in count metric (e.g., entity.count) if available, or COUNT(entity.key_field) on a specific key column.
• Reuse existing attributes and metrics — if a calculated attribute or metric already exists (or you just created one), reference it by name (e.g., entity.attribute_name) rather than repeating its SQL logic in the new metric expression. This keeps definitions DRY and ensures changes propagate.
• Use fully qualified column names — entity.attribute, not just attribute

See reference.md for: aggregation functions, filtered aggregations, date handling, text summarization, data types, metric types, and format strings.

Creation Methods

create_object (Required)

Always use create_object with full YAML to ensure proper datatype and all properties are set.

Call create_object with yaml_text:

type: metric
entity: <entity_name>
name: <snake_case_name>
display_name: <Human Readable Name>
description: |-
  <business description>
owner: <owner_email_or_team>
datatype: float|number|string|date|timestamp
sql: |-
  <aggregation SQL expression>

Required fields:

• type: metric
• entity — the entity this metric belongs to
• name — snake_case identifier
• owner — CRITICAL: always set to current username (from workspace context)
• datatype — CRITICAL: always set explicitly (default to float for most metrics, number for counts)
• sql — the aggregation expression

Optional fields:

• display_name — human readable name
• description — business context
• format_string — display format (e.g., $#,##0.00)
• labels — categorization tags
• folder — organizational path

update_object (for updates)

To modify an existing metric:

1. Use get_entity with the entity name to find the metric and its details.
2. Use search_model (with search_mode: EXACT) to find the metric's object_key.
3. Call update_object with the full updated YAML (yaml_text) and the object_key.

Minimal diff rule: When updating, preserve the existing field order and formatting from the current YAML. Only change the fields you need to modify. Objects are versioned in git, so unnecessary reordering or reformatting creates noisy diffs.

After Creation/Update: Display the UI Link

After a successful create_object or update_object call, the response includes a ui_url field. Always display this URL to the user so they can quickly open the object in the Honeydew application.

delete_object (for deletion)

1. Use search_model (with search_mode: EXACT) to find the metric's object_key.
2. Call delete_object with the object_key.

Examples

See examples.md for full worked examples covering: basic, derived, filtered, ratio, count, distinct count, fixed grouping, nested aggregation, text summary, update, and delete.

Discovery Helpers

Use these MCP tools to explore existing metrics:

• get_entity — Get entity details including all its metrics, attributes, datasets, and relations
• get_field — Get detailed info about a specific metric by entity and field name
• search_model — Search for metrics across the model by name (use search_mode: EXACT for known names, OR for broad discovery)
• list_entities — List entities to identify where to anchor new metrics

Clarify Ambiguous Requests (BEFORE creating)

Many metric requests are ambiguous. ALWAYS clarify before implementing:

Map User Choice → Implementation Pattern

After user clarifies intent, use the correct SQL pattern:

CRITICAL: "Breakdown by X" or "for each X" = Fixed GROUP BY

• ✅ SUM(order_header.order_total) GROUP BY (order_header.order_date)
• ❌ SUM(order_header.order_total) ← requires manual grouping at query time

Additional Grouping Clarifications

When the user's request contains phrases suggesting a specific granularity, ask before creating:

Rule: If the request mentions "per X" or "in an X", clarify whether they want:

1. Fixed Grouping — SUM(entity.field) GROUP BY (entity.x_id)
2. Flexible Aggregation — SUM(entity.field) that users can group by anything later

Documentation Lookup

Use the honeydew-docs MCP tools to search the Honeydew documentation when:

• You need to understand metric types or advanced aggregation patterns beyond what reference.md covers
• The user asks about how metrics behave in BI tools or how context-sensitive aggregation works
• You need guidance on derived metrics, fixed groupings, or metric composition patterns
• The user needs time intelligence features — period-over-period comparisons, YTD/MTD/QTD calculations, trailing windows, or time-based growth metrics

Search for topics like: "metrics", "aggregation", "derived metrics", "fixed grouping", "time intelligence", "period over period", "YTD", "trailing window".

Best Practices

• Use FILTER (WHERE ...) for filtered aggregations — NOT CASE WHEN. The FILTER syntax is cleaner, more readable, and the native Honeydew pattern.
  • ✅ SUM(orders.amount) FILTER (WHERE orders.is_promotional)
  • ✅ COUNT(truck.truck_id) FILTER (WHERE truck.is_electric)
  • ❌ SUM(CASE WHEN orders.is_promotional THEN orders.amount ELSE 0 END)
  • ❌ COUNT(CASE WHEN truck.is_electric THEN truck.truck_id END)
• Reuse existing objects — don't repeat logic. If you created a calculated attribute (e.g., orders.net_price), reference it in your metric (SUM(orders.net_price)) rather than inlining the attribute's SQL expression. Similarly, if a metric already exists, reference it in derived metrics by name (entity.existing_metric). This keeps definitions DRY and ensures changes propagate automatically.
• Never use COUNT(*). Use the entity's built-in count metric (e.g., entity.count) when available. Otherwise, use COUNT(entity.key_field) on the entity's key column.
• Name metrics after the business concept, not the SQL. gross_margin is better than revenue_minus_cogs_divided_by_revenue.
• Use Derived metrics for ratios. Build numerator and denominator as separate metrics first.
• Use fully qualified column names. orders.amount, not just amount.
• Ignore grouping requests. Build the aggregation; users add dimensions later.

MANDATORY: Validate After Creating

After creating ANY metric, you MUST invoke the validation skill to test and validate results.

See validation skill for:

• How to execute metrics via get_data_from_fields
• Sanity checks (magnitude, sign, consistency)
• When to alert the user about suspicious results
• Cross-validation with related metrics

Quick validation:

Call get_data_from_fields with:

• metrics: ["<entity>.<metric_name>"]

Common Pitfalls to Avoid

• Using COUNT(*) — use the entity's built-in count metric if available, or COUNT(entity.key_field) on a specific key.
• Repeating logic that already exists — if a calculated attribute or metric already exists, reference it by name instead of duplicating its SQL.
• Using window functions — only aggregations allowed in metrics.
• Using joins or subqueries — simple expressions only.
• Unqualified column references — always prefix with entity name.