> ## Documentation Index
> Fetch the complete documentation index at: https://developers.myhero.so/llms.txt
> Use this file to discover all available pages before exploring further.

# Set computed

> Configure a computed ("Formula") column from a plain-language description of a calculation. Reference other columns by wrapping their column id in , e.g…

`set_computed`

Configure a computed ("Formula") column from a plain-language description of a calculation. Reference other columns by wrapping their column id in \{\{col:\<columnId>}}, e.g. "30 days after \{\{col:abc123}}" — get column ids from get\_table\_data or add\_column's response, never invent one. The description compiles ONCE into a typed expression tree, which then evaluates for every row and backfills them immediately. The columns referenced MUST already have data before calling this — the compiler previews against real rows and the backfill runs right away. The description must describe a CALCULATION (dates, numbers, text, booleans) — a description that needs human judgment (e.g. "summarize the risk") is rejected by the compiler.

## Parameters

<ParamField path="tableId" type="string" required />

<ParamField path="columnId" type="string" required>
  The column to configure. Must already exist — create it first with add\_column.
</ParamField>

<ParamField path="description" type="string" required>
  Plain text describing the calculation, with other columns referenced:\<columnId>}}. E.g. "30 days after \{\{col:abc123}}" or "\{\{col:price}} times \{\{col:quantity}}".
</ParamField>