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

# What is a grader?

A **grader** checks conversation evidence and assigns a score from `0` to `1`.
A **grade** records that score, the supporting details, and the grader's pass
threshold. A score at or above the threshold passes that grader's check.

A metric records an observed fact, such as response latency. A grader can use
that metric to decide whether the conversation meets a requirement.

## Add or update a grader

[Add a grader](/docs/platform/graders/add-a-grader) from the library, or [create a custom grader](/docs/platform/graders/custom-graders) for your own rules. [Update a grader](/docs/platform/graders/configure-graders) to change its scope and settings.

## Choose a grader

Read [Types of graders](/docs/platform/graders/types) to choose between language
model checks and code-based checks.

## Choose where a grader applies

Add graders to your project and configure their scope, settings, and pass
thresholds. A scope can select simulations or a sample of production
conversations. Expected behaviors always grades simulations and does not
grade production conversations.

Read [Configure graders](/docs/platform/graders/configure-graders) for the available
scope controls and regrading.

## Read each result

A grader can fail to produce a score when evidence is missing or grading
fails. Check its state and evidence. A missing score is not a pass.

Each grader has its own result. The combined score is the mean of the selected
grader scores and does not decide an overall pass or fail. See
[Scores and thresholds](/docs/platform/graders/scores-and-thresholds).