Interface: ToolDefinition<TInput, TOutput, TName>

Defined in: tools/tool-definition.ts:99

Tool definition builder that allows creating server or client tools from a shared definition

Extends

• ToolDefinitionInstance<TInput, TOutput, TName>

Type Parameters

TInput

TInput extends SchemaInput = z.ZodType

TOutput

TOutput extends SchemaInput = z.ZodType

TName

TName extends string = string

Properties

__toolSide

__toolSide: "definition";

__toolSide: "definition";

Defined in: tools/tool-definition.ts:43

Inherited from

ToolDefinitionInstance.__toolSide

client()

client: (execute?) => ClientTool<TInput, TOutput, TName>;

client: (execute?) => ClientTool<TInput, TOutput, TName>;

Defined in: tools/tool-definition.ts:116

Create a client-side tool with optional execute function

Parameters

execute?

(args) => | InferSchemaType<TOutput> | Promise<InferSchemaType<TOutput>>

Returns

ClientTool<TInput, TOutput, TName>

description

description: string;

description: string;

Defined in: types.ts:343

Clear description of what the tool does.

This is crucial - the model uses this to decide when to call the tool. Be specific about what the tool does, what parameters it needs, and what it returns.

Example

"Get the current weather in a given location. Returns temperature, conditions, and forecast."

"Get the current weather in a given location. Returns temperature, conditions, and forecast."

Inherited from

ToolDefinitionInstance.description

execute()?

optional execute: (args) => any;

optional execute: (args) => any;

Defined in: types.ts:414

Optional function to execute when the model calls this tool.

If provided, the SDK will automatically execute the function with the model's arguments and feed the result back to the model. This enables autonomous tool use loops.

Can return any value - will be automatically stringified if needed.

Parameters

args

any

The arguments parsed from the model's tool call (validated against inputSchema)

Returns

any

Result to send back to the model (validated against outputSchema if provided)

Example

execute: async (args) => {
  const weather = await fetchWeather(args.location);
  return weather; // Can return object or string
}

execute: async (args) => {
  const weather = await fetchWeather(args.location);
  return weather; // Can return object or string
}

Inherited from

ToolDefinitionInstance.execute

inputSchema?

optional inputSchema: TInput;

optional inputSchema: TInput;

Defined in: types.ts:375

Schema describing the tool's input parameters.

Can be either a Zod schema or a JSON Schema object. Defines the structure and types of arguments the tool accepts. The model will generate arguments matching this schema. Zod schemas are converted to JSON Schema for LLM providers.

See

• https://zod.dev/
• https://json-schema.org/

Examples

// Using Zod schema
import { z } from 'zod';
z.object({
  location: z.string().describe("City name or coordinates"),
  unit: z.enum(["celsius", "fahrenheit"]).optional()
})

// Using Zod schema
import { z } from 'zod';
z.object({
  location: z.string().describe("City name or coordinates"),
  unit: z.enum(["celsius", "fahrenheit"]).optional()
})

// Using JSON Schema
{
  type: 'object',
  properties: {
    location: { type: 'string', description: 'City name or coordinates' },
    unit: { type: 'string', enum: ['celsius', 'fahrenheit'] }
  },
  required: ['location']
}

// Using JSON Schema
{
  type: 'object',
  properties: {
    location: { type: 'string', description: 'City name or coordinates' },
    unit: { type: 'string', enum: ['celsius', 'fahrenheit'] }
  },
  required: ['location']
}

Inherited from

ToolDefinitionInstance.inputSchema

metadata?

optional metadata: Record<string, any>;

optional metadata: Record<string, any>;

Defined in: types.ts:420

Additional metadata for adapters or custom extensions

Inherited from

ToolDefinitionInstance.metadata

name

name: TName;

name: TName;

Defined in: types.ts:333

Unique name of the tool (used by the model to call it).

Should be descriptive and follow naming conventions (e.g., snake_case or camelCase). Must be unique within the tools array.

Example

"get_weather", "search_database", "sendEmail"

"get_weather", "search_database", "sendEmail"

Inherited from

ToolDefinitionInstance.name

needsApproval?

optional needsApproval: boolean;

optional needsApproval: boolean;

Defined in: types.ts:417

If true, tool execution requires user approval before running. Works with both server and client tools.

Inherited from

ToolDefinitionInstance.needsApproval

outputSchema?

optional outputSchema: TOutput;

optional outputSchema: TOutput;

Defined in: types.ts:395

Optional schema for validating tool output.

Can be either a Zod schema or a JSON Schema object. If provided with a Zod schema, tool results will be validated against this schema before being sent back to the model. This catches bugs in tool implementations and ensures consistent output formatting.

Note: This is client-side validation only - not sent to LLM providers. Note: JSON Schema output validation is not performed at runtime.

Example

z.object({
  temperature: z.number(),
  conditions: z.string(),
  forecast: z.array(z.string()).optional()
})

z.object({
  temperature: z.number(),
  conditions: z.string(),
  forecast: z.array(z.string()).optional()
})

Inherited from

ToolDefinitionInstance.outputSchema

server()

server: (execute) => ServerTool<TInput, TOutput, TName>;

server: (execute) => ServerTool<TInput, TOutput, TName>;

Defined in: tools/tool-definition.ts:107

Create a server-side tool with execute function

Parameters

execute

(args) => | InferSchemaType<TOutput> | Promise<InferSchemaType<TOutput>>

Returns

ServerTool<TInput, TOutput, TName>