---
title: "Reuse before you rebuild - Atlan MCP Cookbook"
url: "https://atlan.com/mcp-cookbook/reuse-before-you-rebuild/"
description: "Before you write SQL to derive a metric, check whether it already exists - and reuse the governed one."
---

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Recipe 3 in [The Atlan MCP Cookbook](https://atlan.com/mcp-cookbook/). Before you write SQL to derive a metric, check whether it already exists - and reuse the governed one.

Use case: Find & understand data / Action: Look up / Persona: AI Builder, Data Engineer / Effort: Quick / Runs in: any AI tool

Requires Atlan MCP connected to your AI tool: [set up Atlan MCP](https://docs.atlan.com/product/capabilities/atlan-ai/how-tos/remote-mcp-overview).

## 1. The task

**Scenario.** Someone's about to write SQL to derive MRR for a new exec view. The risk isn't the work; it's ending up with a second, slightly-different definition of a number the company already calculates. Check where it already lives first.

The ask:
- Where the metric is already materialized
- The best existing implementation to reuse
- A reuse-or-rebuild verdict

Hero prompt:

> Does MRR already exist somewhere I can reuse before I build it?

Step by step:

1. Find the metric's governed term. Prompt: "I'm about to derive [metric] - find its governed term in Atlan first."
2. Find everywhere it's already materialized. Prompt: "Show every certified asset linked to that term where [metric] already lives."
3. Recommend the single best one to reuse. Prompt: "Give me the one certified asset to reuse, with its owner and location, and a reuse-or-rebuild verdict."

## 2. What you'll give it

Required context:
- The metric you're about to build (and its governed term, if you know it)

Optional context:
- Where the new asset will live, so the recommendation fits your stack
- Works from a ticket, a Slack ask, or ad hoc

## 3. What Atlan creates

Outputs:
- Everywhere the metric is already materialized - e.g. MRR across ~30 assets
- The best one to reuse - e.g. a certified warehouse column such as executive_summary.total_monthly_recurring_revenue, plus the BI copies that already report it
- A one-line verdict: reuse the certified column, don't re-derive - one governed definition, not two

**Summary.** A duplicate model you just didn't build. Reuse the governed number instead of minting a second, slightly-different one.

**Read-only.** Nothing is written - it searches and recommends; you decide what to reuse.

## 4. Follow-up prompts

- **Compare the options:** "Between the top two, which is the certified one and which do more teams already use?"
- **Confirm it's official:** "Is the column I'd reuse linked to the governed term, so I know it's the official calc?"
- **Get access:** "Who owns it and how do I get access to reuse it?"

## 5. Tips & troubleshooting

**Cook's note.** Reuse the certified implementation. A second definition of the same metric is how two dashboards start disagreeing.

- Match the tool to the work. Any AI tool works; it reads and recommends, so it's safe to run before any build.
- Automate or chain it. Chain it into your modeling workflow: before a new metric model is written, check for an existing governed one.
- It only reads. No writes - pairs naturally with "Understand how a metric is calculated" (confirm the definition, then reuse it).

## Related recipes

- [Understand how a metric is calculated](https://atlan.com/mcp-cookbook/understand-how-a-metric-is-calculated/): Get the governed definition of a metric - and where it's documented - without asking a data engineer.
- [Get build-ready for a new dashboard](https://atlan.com/mcp-cookbook/get-build-ready-for-a-new-dashboard/): Before you build a dashboard: the trusted source, the confirmed definition, and how the data is really used - as the build recipe.
- [Trace a broken dashboard to its root cause](https://atlan.com/mcp-cookbook/trace-a-broken-dashboard-to-its-root-cause/): Trace lineage upstream from a broken dashboard to find the source of wrong numbers.

[Browse all recipes](https://atlan.com/mcp-cookbook/) / [Set up Atlan MCP](https://docs.atlan.com/product/capabilities/atlan-ai/how-tos/remote-mcp-overview)