Strict Mode

Strict mode ensures the model strictly follows the JSON Schema format when generating function calls. When enabled, the SDK automatically:

1. Sends the request to the DeepSeek Beta endpoint (https://api.deepseek.com/beta)
2. Passes strict: true in all tool definitions to the API
3. Enforces that all object properties are required and sets additionalProperties: false

The server validates the JSON Schema and returns an error if it doesn't conform to the supported schema types.

There are two ways to enable strict mode:

Model-Level Strict (Recommended)

Set strict: true on the model to enable strict mode for all tool calls globally:

const model = createModel({ model: 'deepseek-v4-flash', strict: true })

When using model-level strict, all tools in requests will automatically have strict: true — you don't need to set it on each tool individually. The SDK also automatically switches to the Beta endpoint via model.enableBeta().

You can also manually trigger Beta endpoint switching:

const model = createModel({ model: 'deepseek-v4-flash' })
model.enableBeta() // Switches baseURL to https://api.deepseek.com/beta/

Per-Tool Strict

Set strict: true on individual tools. All tools in the same request must have the same strict value — mixing strict and non-strict tools is not allowed:

const searchTool = tool({
  name: 'search',
  description: 'Search records in the database',
  schema: z.object({
    query: z.string().describe('Search keywords'),
    limit: z.number().describe('Maximum number of results'),
  }),
  strict: true,
  execute: async (input) => {
    return { results: [], total: 0 }
  },
})

When any tool has strict: true, the SDK automatically detects this and switches to the Beta endpoint before sending the request.

Type Safety

TypeScript enforces consistency at compile time through dedicated types:

• StrictTool[] — All tools must have strict: true
• NonStrictTool[] — All tools have strict: false or undefined
• ConsistentTools = StrictTool[] | NonStrictTool[] — Union type used by generateText and agent methods

A runtime validation via validateToolConsistency() is also performed as a fallback, throwing an error if strict and non-strict tools are mixed.

Supported JSON Schema Types

Strict mode supports a subset of JSON Schema types. Using unsupported types will result in a server-side error: