getScorer()

The getScorer() method retrieves a specific scorer that was registered with the Mastra instance using its registration key. The method provides type-safe access to scorers and throws an error if the requested scorer isn't found.

Usage example

import { mastra } from './mastra'

// Get a specific scorer by key
const relevancyScorer = mastra.getScorer('relevancyScorer')

const weatherAgent = mastra.getAgent('weatherAgent')

// Use the scorer to evaluate an AI output
await weatherAgent.generate('What is the weather in Rome', {
  scorers: {
    answerRelevancy: {
      scorer: relevancyScorer,
    },
  },
})

Parameters

key:

string

The registration key of the scorer to retrieve. This should match a key used when registering scorers in the Mastra constructor.

Returns

scorer:

MastraScorer

The MastraScorer instance associated with the provided key.

Error handling

This method throws a MastraError if:

• The scorer with the specified key isn't found
• No scorers are registered with the Mastra instance

try {
  const scorer = mastra.getScorer('nonExistentScorer')
} catch (error) {
  if (error.id === 'MASTRA_GET_SCORER_NOT_FOUND') {
    console.log('Scorer not found, using default evaluation')
  }
}

Related

• listScorers(): Get all registered scorers
• getScorerById(): Get a scorer by its id property
• Custom Scorers: Learn how to create custom scorers