---
title: "Evals & Scorers | v1 Migration Guide"
description: "Learn how to migrate evals and scorers changes when upgrading to v1."
---

# Evals & Scorers

The evaluation API has been consolidated on the new scorers system with updated naming conventions and configuration requirements.

## Changed

### `getScorers` to `listScorers`

The `getScorers()` method has been renamed to `listScorers()`. This change aligns with the naming convention used across the API where plural getter methods use the `list` prefix.

To migrate, replace all calls to `getScorers()` with `listScorers()`.

```diff
- const scorers = mastra.getScorers();
+ const scorers = mastra.listScorers();
```

:::tip[Codemod]

You can use Mastra's codemod CLI to update your code automatically:

```shell
npx @mastra/codemod@beta v1/mastra-plural-apis .
```

:::

### `runExperiment` to `runEvals`

The `runExperiment()` function has been renamed to `runEvals()`. This change provides clearer naming that better describes the evaluation functionality.

To migrate, update function calls from `runExperiment` to `runEvals`.

```diff
- import { createScorer, runExperiment } from '@mastra/core/evals';
+ import { createScorer, runEvals } from '@mastra/core/evals';
  import { myAgent } from './agents/my-agent';

  const scorer = createScorer({
    id: 'helpfulness-scorer',
    // ...
  });

- const result = await runExperiment({ target: myAgent, scorers: [scorer], data: inputs });
+ const result = await runEvals({ target: myAgent, scorers: [scorer], data: inputs });
```

:::tip[Codemod]

You can use Mastra's codemod CLI to update your code automatically:

```shell
npx @mastra/codemod@beta v1/evals-run-experiment .
```

:::

### `getScorerByName` to `getScorerById`

The `getScorerByName()` method has been renamed to `getScorerById()`. Scorers now require an `id` field instead of `name`. This change aligns with the broader API pattern of using `id` for entity identification.

To migrate, update method calls and scorer configuration to use `id` instead of `name`.

```diff
  const scorer = createScorer({
-   name: 'helpfulness-scorer',
+   id: 'helpfulness-scorer',
    // ...
  });
  
- const scorer = mastra.getScorerByName('helpfulness-scorer');
+ const scorer = mastra.getScorerById('helpfulness-scorer');
```

:::tip[Codemod]

You can use Mastra's codemod CLI to update your code automatically:

```shell
npx @mastra/codemod@beta v1/evals-scorer-by-name .
```

:::

### Scorer configuration from `name` to `id`

Scorers now require an `id` field instead of `name`. The `name` field is now optional. This change provides consistency with other Mastra entities.

To migrate, update scorer definitions to use `id` as the required field.

```diff
  const scorer = createScorer({
-   name: 'helpfulness-scorer',
+   id: 'helpfulness-scorer',
+   name: 'Helpfulness Scorer', // optional
    // ...
  });
```

### Storage score APIs to `listScoresBy*` pattern

Score storage APIs have been renamed to follow the `listScoresBy*` pattern. This change aligns with the broader storage API naming conventions.

To migrate, update score query methods to use the new naming pattern.

```diff
- const scores = await storage.getScores({ scorerName: 'helpfulness-scorer' });
+ const scores = await storage.listScoresByScorerId({
+   scorerId: 'helpfulness-scorer',
+ });

// Also available:
// - listScoresByRunId
// - listScoresByEntityId  
// - listScoresBySpan
```

### Prebuilt scorer imports to `scorers/prebuilt` path

Prebuilt scorer imports have been consolidated under a single `@mastra/evals/scorers/prebuilt` path instead of separate `scorers/llm` and `scorers/code` paths. This change simplifies imports and provides a clearer organization of prebuilt scorers.

To migrate, update import statements to use the new `scorers/prebuilt` path.

```diff
  // LLM-based scorers
- import { createHallucinationScorer } from '@mastra/evals/scorers/llm';
- import { createFaithfulnessScorer } from '@mastra/evals/scorers/llm';
+ import { createHallucinationScorer } from '@mastra/evals/scorers/prebuilt';
+ import { createFaithfulnessScorer } from '@mastra/evals/scorers/prebuilt';

  // Code-based scorers
- import { createContentSimilarityScorer } from '@mastra/evals/scorers/code';
- import { createCompletenessScorer } from '@mastra/evals/scorers/code';
+ import { createContentSimilarityScorer } from '@mastra/evals/scorers/prebuilt';
+ import { createCompletenessScorer } from '@mastra/evals/scorers/prebuilt';
```

:::tip[Codemod]

You can use Mastra's codemod CLI to update your code automatically:

```shell
npx @mastra/codemod@beta v1/evals-prebuilt-imports .
```

:::

### Scorer message types from `UIMessage` to `MastraDBMessage`

Scorer input and output types now use `MastraDBMessage[]` instead of `UIMessage`. This change aligns scorers with the database-persisted message format for consistency across the framework.

To migrate, update scorer implementations to use `MastraDBMessage` types and access message content through the nested `content` structure.

```diff
  import type {
    ScorerRunInputForAgent,
    ScorerRunOutputForAgent
  } from '@mastra/core/evals';

- // ScorerRunInputForAgent uses UIMessage[]
- const inputMessages: UIMessage[] = run.input.inputMessages;
+ // ScorerRunInputForAgent now uses MastraDBMessage[]
+ import type { MastraDBMessage } from '@mastra/core/agent';
+ const inputMessages: MastraDBMessage[] = run.input.inputMessages;
```

### Message content structure to nested format

Tool invocations and text content are now accessed through a nested `content` object structure instead of being flat properties on the message. This change provides better type safety and aligns with the database message format.

To migrate, access tool invocations via `message.content.toolInvocations` and text via `message.content.content` or use the `getTextContentFromMastraDBMessage()` helper.

```diff
+ import { getTextContentFromMastraDBMessage } from '@mastra/evals';
+
  const run = await scorer.run(testRun);

  // Accessing text content
- const text = message.content;
+ const text = getTextContentFromMastraDBMessage(message);
+ // or directly: message.content.content

  // Accessing tool invocations
- const toolCalls = message.toolInvocations;
+ const toolCalls = message.content.toolInvocations;
```

## Removed

### Legacy evals code

Legacy evals code has been removed from `@mastra/core`. This includes legacy evaluation metrics, scorer/judge modules, and hook-based automatic evaluation code. This change simplifies the codebase by removing outdated evaluation approaches.

To migrate, use the new evals/scorers API in `@mastra/core/evals` or `@mastra/evals`.

```diff
- // Legacy evals APIs
+ import { createScorer, runEvals } from '@mastra/core/evals';
+ 
+ const scorer = createScorer({
+   id: 'my-scorer',
+   // Use new scorer API
+ });
```

### Agent `TMetrics` generic parameter

The `TMetrics` generic parameter has been removed from `AgentConfig` and the `Agent` constructor. Metrics/scorers are now configured using the scorers API instead of being part of the Agent type system. This change simplifies the Agent type signature.

To migrate, remove the `TMetrics` generic parameter and configure scorers using the scorers API.

```diff
- const agent = new Agent<AgentId, Tools, Metrics>({
+ const agent = new Agent<AgentId, Tools>({
    // ...
  });
```

### Evals-related type exports

Several evals-related type exports have been removed including `DeprecatedOutputOptions`, `Metric`, and processor option types. These types are now internal or have been replaced by the new scorers API. This change reduces API surface area.

To migrate, remove references to these removed types and use the new scorers API.

```diff
- import type {
-   DeprecatedOutputOptions,
-   Metric,
-   LanguageDetectorOptions,
-   ModerationOptions,
- } from '@mastra/core';
+ // Use new scorers API types
+ import type { Scorer } from '@mastra/core/evals';
```

### `createUIMessage` test helper

The `createUIMessage()` test helper has been removed and replaced with `createTestMessage()`. The new helper creates `MastraDBMessage` objects with the nested content structure and supports optional tool invocations. This change aligns test utilities with the new message format.

To migrate, replace `createUIMessage()` calls with `createTestMessage()` and update to use `MastraDBMessage` types.

```diff
- import { createUIMessage } from '@mastra/evals';
+ import { createTestMessage } from '@mastra/evals';

  // Creating test messages
- const message = createUIMessage({
-   id: 'test-1',
+ const message = createTestMessage({
+   id: 'test-1', // optional, defaults to 'test-message'
    role: 'user',
    content: 'Hello',
    toolInvocations: [], // optional
  });
```
