Creating Tools

Learn the patterns and best practices for building CTP-compliant tools.

Tool Structure

Every CTP tool consists of two parts:

Definition - Metadata describing the tool
Function - Implementation that processes inputs

import type { ToolDefinition, ToolFunction } from '@conveniencepro/ctp-core';

// 1. Define result type
interface MyToolResult {
  // ... result properties
}

// 2. Create definition
export const myToolDefinition: ToolDefinition = {
  // ... metadata
};

// 3. Implement function
export const myToolFn: ToolFunction<MyToolResult> = (params) => {
  // ... implementation
};

// 4. Export together
export default { definition: myToolDefinition, fn: myToolFn };

Definition Patterns

Minimal Definition

export const minimalDefinition: ToolDefinition = {
  id: 'minimal-tool',
  name: 'Minimal Tool',
  description: 'A minimal example tool.',
  category: 'utilities',
  tags: ['example'],
  method: 'POST',
  parameters: [
    {
      name: 'input',
      type: 'text',
      label: 'Input',
      description: 'Input value',
      required: true,
    },
  ],
  outputDescription: 'Processed result',
  example: {
    input: { input: 'test' },
    output: { result: 'processed' },
  },
};

Full-Featured Definition

export const fullDefinition: ToolDefinition = {
  // Required
  id: 'advanced-tool',
  name: 'Advanced Tool',
  description: 'A fully-featured example with all options.',
  category: 'formatters',
  tags: ['advanced', 'example', 'featured'],
  method: 'POST',
  parameters: [/* ... */],
  outputDescription: 'Formatted output with metadata',
  example: {
    input: { /* ... */ },
    output: { /* ... */ },
  },

  // Optional metadata
  version: '1.0.0',
  icon: '🔧',
  keywords: ['full', 'complete'],
  relatedTools: ['simple-tool', 'other-tool'],

  // AI guidance
  aiInstructions: 'Use default settings unless user specifies otherwise.',

  // Execution
  executionMode: 'client',
  requiresAuth: false,

  // Rate limiting
  rateLimit: {
    requests: 100,
    window: 60,
  },
};

Implementation Patterns

Synchronous Tool

export const syncFn: ToolFunction<Result> = (params) => {
  const input = params.input as string;

  // Validation
  if (!input) {
    return {
      success: false,
      error: 'Input is required',
      errorCode: 'MISSING_REQUIRED',
    };
  }

  // Processing
  const result = processSync(input);

  // Return success
  return {
    success: true,
    data: result,
  };
};

Asynchronous Tool

export const asyncFn: ToolFunction<Result> = async (params) => {
  const input = params.input as string;

  try {
    // Async operation (e.g., Web Crypto)
    const hash = await crypto.subtle.digest(
      'SHA-256',
      new TextEncoder().encode(input)
    );

    return {
      success: true,
      data: { hash: arrayToHex(hash) },
    };
  } catch (error) {
    return {
      success: false,
      error: (error as Error).message,
      errorCode: 'EXECUTION_ERROR',
    };
  }
};

With Metadata

export const metadataFn: ToolFunction<Result> = (params) => {
  const startTime = performance.now();
  const input = params.input as string;

  const result = process(input);

  return {
    success: true,
    data: result,
    metadata: {
      executionTime: performance.now() - startTime,
      inputSize: input.length,
      outputSize: JSON.stringify(result).length,
    },
  };
};

With Warnings

export const warningFn: ToolFunction<Result> = (params) => {
  const algorithm = params.algorithm as string;
  const warnings: string[] = [];

  if (algorithm === 'SHA-1') {
    warnings.push('SHA-1 is deprecated for security purposes');
  }

  if (algorithm === 'MD5') {
    warnings.push('MD5 is cryptographically broken');
  }

  const result = compute(params);

  return {
    success: true,
    data: result,
    metadata: {
      warnings: warnings.length > 0 ? warnings : undefined,
    },
  };
};

Parameter Patterns

Select with Descriptions

{
  name: 'format',
  type: 'select',
  label: 'Output Format',
  description: 'Choose the output format',
  required: false,
  defaultValue: 'json',
  options: [
    { value: 'json', label: 'JSON', description: 'JavaScript Object Notation' },
    { value: 'yaml', label: 'YAML', description: 'Human-readable format' },
    { value: 'xml', label: 'XML', description: 'Extensible Markup Language' },
  ],
}

Conditional Parameters

parameters: [
  {
    name: 'mode',
    type: 'select',
    label: 'Mode',
    required: true,
    options: [
      { value: 'simple', label: 'Simple' },
      { value: 'advanced', label: 'Advanced' },
    ],
  },
  {
    name: 'advancedOption',
    type: 'text',
    label: 'Advanced Option',
    description: 'Only shown in advanced mode',
    required: false,
    dependsOn: [{ field: 'mode', condition: 'equals', value: 'advanced' }],
  },
]

Grouped Parameters

parameters: [
  // Input group
  { name: 'input', type: 'textarea', group: 'input', order: 1, /* ... */ },

  // Options group
  { name: 'format', type: 'select', group: 'options', order: 1, /* ... */ },
  { name: 'indent', type: 'number', group: 'options', order: 2, /* ... */ },

  // Advanced group
  { name: 'strict', type: 'boolean', group: 'advanced', order: 1, /* ... */ },
]

Bidirectional Tools

Handle encode/decode or similar operations:

export const bidirectionalDefinition: ToolDefinition = {
  id: 'base64-encoder',
  name: 'Base64 Encoder/Decoder',
  // ...
  parameters: [
    {
      name: 'input',
      type: 'textarea',
      label: 'Input',
      description: 'Text to encode or Base64 to decode',
      required: true,
    },
    {
      name: 'mode',
      type: 'select',
      label: 'Mode',
      required: false,
      defaultValue: 'encode',
      options: [
        { value: 'encode', label: 'Encode' },
        { value: 'decode', label: 'Decode' },
      ],
    },
  ],
};

export const bidirectionalFn: ToolFunction<Result> = (params) => {
  const input = params.input as string;
  const mode = (params.mode as 'encode' | 'decode') || 'encode';

  const output = mode === 'encode'
    ? btoa(input)
    : atob(input);

  return {
    success: true,
    data: { output, mode },
  };
};

Error Handling

Validation Errors

if (!input) {
  return {
    success: false,
    error: 'Input is required',
    errorCode: 'MISSING_REQUIRED',
  };
}

if (typeof input !== 'string') {
  return {
    success: false,
    error: 'Input must be a string',
    errorCode: 'TYPE_ERROR',
  };
}

if (input.length > 100000) {
  return {
    success: false,
    error: 'Input exceeds maximum length',
    errorCode: 'CONSTRAINT_VIOLATION',
  };
}

Execution Errors

try {
  const parsed = JSON.parse(input);
  return { success: true, data: { parsed } };
} catch (e) {
  return {
    success: false,
    error: `Invalid JSON: ${(e as Error).message}`,
    errorCode: 'INVALID_INPUT',
    suggestion: 'Check for missing quotes or trailing commas',
  };
}

Testing Tools

import { describe, it, expect } from 'vitest';
import myTool from './my-tool';

describe('my-tool', () => {
  it('returns success for valid input', () => {
    const result = myTool.fn({ input: 'test' });
    expect(result.success).toBe(true);
    expect(result.data).toBeDefined();
  });

  it('returns error for missing input', () => {
    const result = myTool.fn({});
    expect(result.success).toBe(false);
    expect(result.errorCode).toBe('MISSING_REQUIRED');
  });
});

Developer Guide

Advanced

​Creating Tools

​Tool Structure

​Definition Patterns

​Minimal Definition

​Full-Featured Definition

​Implementation Patterns

​Synchronous Tool

​Asynchronous Tool

​With Metadata

​With Warnings

​Parameter Patterns

​Select with Descriptions

​Conditional Parameters

​Grouped Parameters

​Bidirectional Tools

​Error Handling

​Validation Errors

​Execution Errors

​Testing Tools

Creating Tools

Tool Structure

Definition Patterns

Minimal Definition

Full-Featured Definition

Implementation Patterns

Synchronous Tool

Asynchronous Tool

With Metadata

With Warnings

Parameter Patterns

Select with Descriptions

Conditional Parameters

Grouped Parameters

Bidirectional Tools

Error Handling

Validation Errors

Execution Errors

Testing Tools