Agent.generateLegacy() (Legacy)

warning

Deprecated: This method is deprecated and only works with legacy model adapters. For current model adapters, use .generate() instead.

The .generateLegacy() method is the legacy version of the agent generation API, used with legacy model adapters to produce text or structured responses. This method accepts messages and optional generation options.

Usage example

await agent.generateLegacy('message for agent')

Processor retry support

generateLegacy() doesn't run error processors or maxProcessorRetries. It uses the legacy AI SDK generation path instead.

Scorer judges with legacy model adapters call generateLegacy(). They don't receive the coordinated StreamErrorRetryProcessor budget available to scorer judges that use Mastra’s current generation API. Use a current model adapter when you need error-processor retries. The legacy maxRetries option remains separate and defaults to 2.

Parameters

messages:

string | string[] | CoreMessage[] | AiMessageType[] | UIMessageWithMetadata[]

The messages to send to the agent. Can be a single string, array of strings, or structured message objects with multimodal content (text, images, etc.).

options?:

AgentGenerateOptions

Optional configuration for the generation process.

AgentGenerateOptions

abortSignal?:

AbortSignal

Signal object that allows you to abort the agent's execution. When the signal is aborted, all ongoing operations will be terminated.

context?:

CoreMessage[]

Additional context messages to provide to the agent.

structuredOutput?:

StructuredOutputOptions<S extends ZodTypeAny = ZodTypeAny>

Enables structured output generation with better developer experience. Automatically creates and uses a StructuredOutputProcessor internally.

StructuredOutputOptions<S extends ZodTypeAny = ZodTypeAny>

schema:

z.ZodSchema<S>

Zod schema to validate the output against.

model:

MastraLanguageModel

Model to use for the internal structuring agent.

errorStrategy?:

'strict' | 'warn' | 'fallback'

Strategy when parsing or validation fails. Defaults to 'strict'.

fallbackValue?:

<S extends ZodTypeAny>

Fallback value when errorStrategy is 'fallback'.

instructions?:

string

Custom instructions for the structuring agent.

outputProcessors?:

Processor[]

Overrides the output processors set on the agent. Output processors that can modify or validate messages from the agent before they are returned to the user. Must implement either (or both) of the processOutputResult and processOutputStream functions.

inputProcessors?:

Processor[]

Overrides the input processors set on the agent. Input processors that can modify or validate messages before they are processed by the agent. Must implement the processInput function.

experimental_output?:

Zod schema | JsonSchema7

Note, the preferred route is to use the structuredOutput property. Enables structured output generation alongside text generation and tool calls. The model will generate responses that conform to the provided schema.

instructions?:

string

Custom instructions that override the agent's default instructions for this specific generation. Useful for dynamically modifying agent behavior without creating a new agent instance.

output?:

Zod schema | JsonSchema7

Defines the expected structure of the output. Can be a JSON Schema object or a Zod schema.

memory?:

object

Configuration for memory. This is the preferred way to manage memory.

object

thread:

string | { id: string; metadata?: Record<string, any>, title?: string }

The conversation thread, as a string ID or an object with an id and optional metadata.

resource:

string

Identifier for the user or resource associated with the thread.

options?:

MemoryConfig

Configuration for memory behavior, like message history and semantic recall. See MemoryConfig below.

maxSteps?:

number

Maximum number of execution steps allowed.

maxRetries?:

number

Maximum number of retries. Set to 0 to disable retries.

onStepFinish?:

GenerateTextOnStepFinishCallback<any> | never

Callback function called after each execution step. Receives step details as a JSON string. Unavailable for structured output

runId?:

string

Unique ID for this generation run. Useful for tracking and debugging purposes.

telemetry?:

TelemetrySettings

Settings for telemetry collection during generation.

TelemetrySettings

isEnabled?:

boolean

Enable or disable telemetry. Disabled by default while experimental.

recordInputs?:

boolean

Enable or disable input recording. Enabled by default. You might want to disable input recording to avoid recording sensitive information.

recordOutputs?:

boolean

Enable or disable output recording. Enabled by default. You might want to disable output recording to avoid recording sensitive information.

functionId?:

string

Identifier for this function. Used to group telemetry data by function.

temperature?:

number

Controls randomness in the model's output. Higher values (e.g., 0.8) make the output more random, lower values (e.g., 0.2) make it more focused and deterministic.

toolChoice?:

'auto' | 'none' | 'required' | { type: 'tool'; toolName: string }

Controls how the agent uses tools during generation.

'auto' | 'none' | 'required' | { type: 'tool'; toolName: string }

'auto':

string

Let the model decide whether to use tools (default).

'none':

string

Do not use any tools.

'required':

string

Require the model to use at least one tool.

{ type: 'tool'; toolName: string }:

object

Require the model to use a specific tool by name.

toolsets?:

ToolsetsInput

Additional toolsets to make available to the agent during generation.

clientTools?:

ToolsInput

Tools that are executed on the 'client' side of the request. These tools do not have execute functions in the definition.

hooks?:

ToolHooks

Per-execution hooks that run before and after tool calls. Overrides matching agent-level hooks for this execution. beforeToolCall can return { proceed: false, output } to skip the tool call.

savePerStep?:

boolean

Save messages incrementally after each generation step completes (default: false). Disabled internally when observational memory is enabled.

providerOptions?:

Record<string, Record<string, JSONValue>>

Additional provider-specific options that are passed through to the underlying LLM provider. The structure is { providerName: { optionKey: value } }. Since Mastra extends AI SDK, see the AI SDK documentation for complete provider options.

Record<string, Record<string, JSONValue>>

openai?:

Record<string, JSONValue>

OpenAI-specific options. Example: { reasoningEffort: 'high' }

anthropic?:

Record<string, JSONValue>

Anthropic-specific options. Example: { maxTokens: 1000 }

google?:

Record<string, JSONValue>

Google-specific options. Example: { safetySettings: [...] }

[providerName]?:

Record<string, JSONValue>

Other provider-specific options. The key is the provider name and the value is a record of provider-specific options.

requestContext?:

RequestContext

Request Context for dependency injection and contextual information.

maxTokens?:

number

Maximum number of tokens to generate.

topP?:

number

Nucleus sampling. This is a number between 0 and 1. It is recommended to set either temperature or topP, but not both.

topK?:

number

Only sample from the top K options for each subsequent token. Used to remove 'long tail' low probability responses.

presencePenalty?:

number

Presence penalty setting. It affects the likelihood of the model to repeat information that is already in the prompt. A number between -1 (increase repetition) and 1 (maximum penalty, decrease repetition).

frequencyPenalty?:

number

Frequency penalty setting. It affects the likelihood of the model to repeatedly use the same words or phrases. A number between -1 (increase repetition) and 1 (maximum penalty, decrease repetition).

stopSequences?:

string[]

Stop sequences. If set, the model will stop generating text when one of the stop sequences is generated.

seed?:

number

The seed (integer) to use for random sampling. If set and supported by the model, calls will generate deterministic results.

headers?:

Record<string, string | undefined>

Additional HTTP headers to be sent with the request. Only applicable for HTTP-based providers.

Returns

text?:

string

The generated text response. Present when output is 'text' (no schema provided).

object?:

object

The generated structured response. Present when a schema is provided via output, structuredOutput, or experimental_output.

toolCalls?:

Array<ToolCall>

The tool calls made during the generation process. Present in both text and object modes.

Array<ToolCall>

toolName:

string

The name of the tool invoked.

args:

any

The arguments passed to the tool.

Migration to new API

info

The new .generate() method offers enhanced capabilities including AI SDK v5+ compatibility, better structured output handling, and improved streaming support. See the migration guide for detailed migration instructions.

Quick Migration Example

Before (Legacy)

const result = await agent.generateLegacy('message', {
  temperature: 0.7,
  maxSteps: 3,
})

After (New API)

const result = await agent.generate('message', {
  modelSettings: {
    temperature: 0.7,
  },
  maxSteps: 3,
})

Extended usage example

import { z } from 'zod'
import { ModerationProcessor, TokenLimiterProcessor } from '@mastra/core/processors'

await agent.generateLegacy(
  [
    { role: 'user', content: 'message for agent' },
    {
      role: 'user',
      content: [
        {
          type: 'text',
          text: 'message for agent',
        },
        {
          type: 'image',
          imageUrl: 'https://example.com/image.jpg',
          mimeType: 'image/jpeg',
        },
      ],
    },
  ],
  {
    temperature: 0.7,
    maxSteps: 3,
    memory: {
      thread: 'user-123',
      resource: 'test-app',
    },
    toolChoice: 'auto',
    providerOptions: {
      openai: {
        reasoningEffort: 'high',
      },
    },
    // Structured output with better DX
    structuredOutput: {
      schema: z.object({
        sentiment: z.enum(['positive', 'negative', 'neutral']),
        confidence: z.number(),
      }),
      model: 'openai/gpt-5.5',
      errorStrategy: 'warn',
    },
    // Output processors for response validation
    outputProcessors: [
      new ModerationProcessor({ model: 'openai/gpt-5-mini' }),
      new TokenLimiterProcessor({ maxTokens: 1000 }),
    ],
  },
)

Related

• Migration Guide
• New .generate() method
• Generating responses
• Streaming responses