getScorer()

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

• getScorers() - Get all registered scorers
• getScorerByName() - Get a scorer by its name property
• Custom Scorers - Learn how to create custom scorers