powerbi-dax-mastery

powerbi-dax-mastery is a skill for Claude Code, Codex from santoshkanthety/powerbi-agent. It costs 89 tokens per session (1,545 once invoked), scanned A, original, MIT.

A guide to DAX, the formula language used to calculate values in Power BI data models. It explains how measures, calculated columns, filters, rows, and date-based calculations work.

In plain words
What is it for?
Use it to create or fix measures for totals, rankings, year-to-date values, year-over-year comparisons, rolling averages, and running totals.
Why use it?
It helps prevent incorrect results and makes complex calculations easier to diagnose and improve.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to create or fix measures for totals, rankings, year-to-date values, year-over-year comparisons, rolling averages, and running totals.

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Install with agentmods
npx agentmods add skills/santoshkanthety/powerbi-agent/powerbi-dax-mastery
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add santoshkanthety/powerbi-agent --skill powerbi-dax-mastery
Clone the repo
git clone --depth 1 https://github.com/santoshkanthety/powerbi-agent

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for powerbi-dax-mastery

README.md
[![agentmods](https://agentmods.dev/badge/skills/santoshkanthety/powerbi-agent/powerbi-dax-mastery/github.svg)](https://agentmods.dev/skills/santoshkanthety/powerbi-agent/powerbi-dax-mastery)
Your own site
<a href="https://agentmods.dev/skills/santoshkanthety/powerbi-agent/powerbi-dax-mastery"><img src="https://agentmods.dev/badge/skills/santoshkanthety/powerbi-agent/powerbi-dax-mastery/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for powerbi-dax-mastery

Your own site · 80×15
<a href="https://agentmods.dev/skills/santoshkanthety/powerbi-agent/powerbi-dax-mastery"><img src="https://agentmods.dev/badge/skills/santoshkanthety/powerbi-agent/powerbi-dax-mastery.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 89 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,545 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00089 $0.01545
Opus 5 $0.00044 $0.00772
Sonnet 5 $0.00018 $0.00309
Haiku 4.5 $0.00009 $0.00154

Measured 12d ago against content hash 2430727cba95, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

powerbi-dax-mastery scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/powerbi-dax-mastery/SKILL.md · 185 lines

How it starts

The opening of the file, as written. The whole thing — 185 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill: DAX Mastery

Trigger

Activate when the user mentions: DAX, measure, calculated column, calculate, filter context, row context, time intelligence, SUMX, CALCULATE, ALL, ALLEXCEPT, RANKX, TREATAS, YTD, YoY, MTD, rolling average, running total, DAX error, formula, expression, context transition

What You Know

You are a DAX expert who has written thousands of production measures for Fortune 500 companies. You understand evaluation context deeply, know every time intelligence pattern, and can diagnose slow measures by reading a query plan.

Core Principles

Rule 1: Measures vs Calculated Columns

  • Measure = computed at query time, respects filter context → use for everything aggregated
  • Calculated column = computed at refresh time, stored in model → use ONLY for row-level attributes you cannot get via relationships
  • ❌ Never create a calculated column for something you can compute in a measure

Rule 2: Understanding Evaluation Context

-- Filter context = the filters applied by slicers, rows/columns, visual filters
-- Row context = "current row" inside SUMX, FILTER, ADDCOLUMNS iterations

-- This FAILS (CALCULATE needed for context transition):
Wrong Measure = SUMX(Sales, Sales[Amount] * [Margin %])  -- [Margin %] is a measure

-- This WORKS:
Correct Measure = SUMX(Sales, Sales[Amount] * CALCULATE([Margin %]))

Rule 3: CALCULATE is the Engine of DAX

-- CALCULATE(expression, [filter1], [filter2], ...)
-- It does TWO things:
-- 1. Evaluates expression in a NEW filter context
-- 2. Merges/overrides the current filter context

Total Sales = SUM(Sales[Amount])

Sales USA = CALCULATE([Total Sales], Geography[Country] = "USA")

-- ALL() removes filters; ALLEXCEPT() removes all except listed columns
Sales All Products = CALCULATE([Total Sales], ALL(Product))

-- KEEPFILTERS() adds rather than replaces
Sales High Value = CALCULATE([Total Sales], KEEPFILTERS(Sales[Amount] > 1000))

Time Intelligence Patterns

Prerequisites: Always mark your date table

  • One row per date, no gaps
  • Date column as primary key
  • Mark as Date Table in Power BI

Read the full file on GitHub · 185 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 12d ago First seen · 185 lines · 0 tokens per session scan A 2430727cba95

Subscribe to this mod's changes

powerbi-dax-mastery is a skill published in the GitHub repository santoshkanthety/powerbi-agent (2 stars, last pushed 13d ago), licensed MIT. It adds 89 tokens to every session and 1,545 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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