Tools

Tools are reusable functions that agents can call to perform specific actions like processing payments, sending emails, or updating databases.

Tool Structure

Every tool must implement the Tool interface:

interface Tool<Input extends z.ZodSchema, Memory> {
  name: string; // Unique tool identifier
  description: string; // What the tool does (used by LLM)
  input: Input; // Zod schema for input validation
  isGlobal?: boolean; // Optional: available across all LLM calls
  execute: ({ input, state, agent }) => Promise<{ result? }>;
}

Execute Function Signature

The execute function is the core of every tool. It receives validated input from the LLM, current state (including memory), and the agent instance, then modifies state by reference and returns an optional result.

Parameters

execute: ({ input, state, agent }) => Promise<{ result? }>;

• input: Validated data matching your Zod schema - contains the parameters the LLM extracted from the conversation

• state: Current conversation state including memory, sessionId, and other context data

• agent: Agent instance providing access to PII gateway, logging, and other platform features

Return Value

The execute function returns a Promise with an object containing:

• result? (optional): Result that gets sent back to the LLM as the tool's response

Important v2.0 Change: State is now updated by reference directly within the execute function. You no longer return state updates - instead, modify the state object directly.

State Object Structure

The state object contains:

• memory: Your user-defined memory schema - the main working memory for your agent

• sessionId: Unique identifier for the current session

• messages: Array of conversation messages (AI, Human, System, etc.)

• history: Array of HistoryStep objects tracking the flow execution (node visits, trigger events, tool calls)

• Other platform context: Additional fields managed by the platform

Basic Tool Example

Here's a simple refund processing tool:

import { z } from 'zod';
import { Tool } from 'mindedjs/src/types/Tools.types';
import { logger } from 'mindedjs';
import memorySchema from '../schema';

type Memory = z.infer<typeof memorySchema>;

const schema = z.object({
  orderId: z.string(),
  customerName: z.string(),
});

const refundOrderTool: Tool<typeof schema, Memory> = {
  name: 'refundOrder',
  description: 'Process a customer refund for their order',
  input: schema,
  execute: async ({ input, state, agent }) => {
    // Access current memory
    const currentMemory = state.memory;

    // Use the provided logger [[memory:4133901]]
    logger.info('Processing refund', {
      sessionId: state.sessionId,
      orderId: input.orderId,
    });

    // Your business logic here
    const refundAmount = await processRefundInSystem(input.orderId);

    // Update state directly by reference (v2.0 change)
    state.memory.orderId = input.orderId;
    state.memory.customerName = input.customerName;
    state.memory.issue = `Refund processed: $${refundAmount}`;

    // Only return result, no state
    return {
      result: `Refund processed successfully for order ${input.orderId}`,
    };
  },
};

export default refundOrderTool;

Input Schema Configuration

Input schemas use Zod for validation and provide important metadata to help the LLM understand how to better use each input parameter.

Parameter Descriptions

Add descriptions to parameters using Zod's .describe() method. These descriptions help the LLM understand what each parameter represents:

const schema = z.object({
  orderId: z.string().describe('The unique identifier of the customer order to process'),
  customerName: z.string().describe('Full name of the customer requesting the refund'),
  refundAmount: z.number().describe('Amount to refund in dollars (optional if full refund)'),
  reason: z.string().describe('Reason for the refund request'),
});

Optional Parameters

Make parameters optional using Zod's .optional() method. Optional parameters don't need to be provided by the LLM:

const schema = z.object({
  orderId: z.string().describe('The unique identifier of the customer order'),
  customerName: z.string().describe('Full name of the customer'),
  refundAmount: z.number().optional().describe('Specific refund amount, defaults to full order amount'),
  expedited: z.boolean().optional().describe('Whether to expedite the refund process'),
});

Combining Descriptions and Optional Parameters

You can chain Zod methods to create descriptive optional parameters:

const updateOrderSchema = z.object({
  orderId: z.string().describe('The order ID that needs to be updated'),
  newAddress: z.string().optional().describe('Updated shipping address if customer wants to change it'),
  specialInstructions: z.string().optional().describe('Any special delivery instructions from the customer'),
  urgentDelivery: z.boolean().optional().describe('Whether customer needs urgent delivery (additional charges may apply)'),
});

Tool Registration

Global Tools

Mark tools as global if you want them to be available in all LLM calls.

const auditLogTool: Tool<typeof auditSchema, Memory> = {
  name: 'auditLog',
  description: 'Log user action for compliance',
  isGlobal: true, // Available in all flows
  input: z.object({
    action: z.string(),
    details: z.string(),
  }),
  execute: async ({ input, state, agent }) => {
    logger.info('Audit log entry', {
      sessionId: state.sessionId,
      action: input.action,
    });

    await auditService.log({
      userId: state.memory.userId,
      action: input.action,
      details: input.details,
      timestamp: new Date(),
    });

    // No return value needed for tools that don't produce results
    return {};
  },
};

Global vs Non-Global Tools

Feature	Non-Global Tools	Global Tool
Execution	Guaranteed when node is reached	Only when LLM decides to call
Control	Explicit flow control	LLM-driven decision
Use Case	Required business logic steps	Flexible, context-dependent actions

State Management

Tools can read and update state including memory by reference:

const updateProfileTool: Tool<typeof profileSchema, Memory> = {
  name: 'updateProfile',
  description: 'Update customer profile information',
  input: z.object({
    field: z.string(),
    value: z.string(),
  }),
  execute: async ({ input, state, agent }) => {
    // Read current memory from state
    console.log(`Current customer: ${state.memory.customerName}`);

    // Update external system
    await profileService.update(state.memory.customerId, {
      [input.field]: input.value,
    });

    // Update state directly by reference (v2.0 change)
    state.memory[`${input.field}Updated`] = true;

    // No state in return value
    return {};
  },
};

Error Handling

Handle errors gracefully in tools:

const paymentTool: Tool<typeof paymentSchema, Memory> = {
  name: 'processPayment',
  description: 'Process customer payment',
  input: z.object({
    amount: z.number(),
    cardToken: z.string(),
  }),
  execute: async ({ input, state, agent }) => {
    try {
      const result = await paymentService.charge({
        amount: input.amount,
        cardToken: input.cardToken,
        customerId: state.memory.customerId,
      });

      // Update state directly by reference
      state.memory.lastPaymentId = result.transactionId;

      return {
        result: `Payment successful: ${result.transactionId}`,
      };
    } catch (err) {
      logger.error({
        message: 'Payment failed',
        sessionId: state.sessionId,
        err,
      });

      // Update state directly by reference
      state.memory.paymentError = err.message;

      return {
        result: 'Payment failed. Please try again or contact support.',
      };
    }
  },
};

Flow Control with goto

Tools can control the flow by setting the goto property directly on the state object. This allows tools to programmatically jump to a specific node by setting state.goto to the target node ID. This is useful for dynamic flow control based on runtime conditions.

Basic goto Usage

const moveToAnotherRepresentativeTool: Tool<typeof schema, Memory> = {
  name: 'moveToAnotherRepresentative',
  description: 'Transfer the conversation to another representative or department',
  input: schema,
  execute: async ({ input, state }) => {
    logger.info({
      message: 'Moving conversation to another representative',
      sessionId: state.sessionId,
      department: input.department,
      reason: input.reason,
      priority: input.priority,
    });

    // Update state directly by reference (v2.0 change)
    state.goto = 'share-new-representative';
    state.memory.orderId = 'share-new-representative';

    return {};
  },
};

Dynamic Routing Example

const routingTool: Tool<typeof routingSchema, Memory> = {
  name: 'routingTool',
  description: 'Route conversation based on urgency',
  input: routingSchema,
  execute: async ({ input, state }) => {
    // Perform logic to determine routing
    if (input.condition === 'urgent') {
      // Jump to urgent handler node by updating state directly
      state.goto = 'urgent-handler-node';

      return {
        result: 'Routing to urgent handler',
      };
    }

    // Normal flow continues
    return { result: 'Continue normal flow' };
  },
};

Important: The jump occurs only when the current invocation completes and the next one begins. The agent will finish executing the current node/tool before jumping to the specified node.

Best Practices

1. Clear Descriptions: Write descriptions that help the LLM understand when to use the tool

2. Input Validation: Use Zod schemas to validate all inputs

3. State Updates: Update state directly by reference - modify only the parts that need to change

4. Error Handling: Always handle errors gracefully and provide meaningful messages

5. Async Operations: Use async/await for external API calls and database operations

6. Logging: Use the provided logger for consistent, structured logging with session context

Tool Nodes

Tool nodes force execution of specific tools at defined points in your flow, bypassing LLM decision-making.

Configuration

nodes:
  - name: 'Force Refund Processing'
    type: 'tool'
    toolName: 'refundOrder'

Overriding Tool Input Parameters

Tool input parameters' values are inferred by an LLM during runtime. You can override specific input parameters directly in your flow YAML to ensure deterministic values.

nodes:
  - name: 'Send Notification'
    type: 'tool'
    toolName: 'sendEmail'
    parameters:
      recipient: '{state.memory.customerEmail}'
      template: 'order-confirmation'
      priority: 'high'

See Also

• RPA Tools Documentation - RPA tool development guide

• Node Types - Using tools in flow nodes