---
title: Functions
description: Public API reference for the MCP extension
---

## Extension Entry Points

| Function | Description |
|---|---|
| `NewExtension(opts ...ConfigOption) forge.Extension` | Create the MCP extension with functional options |
| `NewExtensionWithConfig(config Config) forge.Extension` | Create the MCP extension with a complete config |
| `DefaultConfig() Config` | Returns the default configuration |

## Server -- Tool Operations

| Method | Description |
|---|---|
| `RegisterTool(tool Tool) error` | Register a tool with name, description, schema, and handler |
| `ListTools() []Tool` | List all registered tools |
| `ExecuteTool(ctx, name, arguments) (*ToolResult, error)` | Execute a named tool with arguments |
| `GenerateToolFromRoute(route) (*Tool, error)` | Generate a tool definition from a Forge HTTP route |

## Server -- Resource Operations

| Method | Description |
|---|---|
| `RegisterResource(resource Resource, reader ResourceReader) error` | Register a resource with a reader function |
| `ListResources() []Resource` | List all registered resources |
| `ReadResource(ctx, uri) (*ResourceContents, error)` | Read a resource by URI |

## Server -- Prompt Operations

| Method | Description |
|---|---|
| `RegisterPrompt(prompt Prompt, generator PromptGenerator) error` | Register a prompt template with a generator function |
| `ListPrompts() []Prompt` | List all registered prompts |
| `GetPrompt(ctx, name, arguments) ([]PromptMessage, error)` | Generate prompt messages from a template |

## Server -- Info

| Method | Description |
|---|---|
| `GetServerInfo() ServerInfo` | Get server name, version, and capabilities |

## Middleware

| Function | Description |
|---|---|
| `AuthMiddleware(config, logger) forge.PureMiddleware` | Create authentication middleware for MCP endpoints |
| `RateLimitMiddleware(config, logger, metrics) forge.PureMiddleware` | Create rate limiting middleware |

## Key Types

### `Tool`

| Field | Type | Purpose |
|---|---|---|
| `Name` | `string` | Tool identifier |
| `Description` | `string` | Human-readable description for AI agents |
| `InputSchema` | `JSONSchema` | JSON Schema describing expected arguments |

### `Resource`

| Field | Type | Purpose |
|---|---|---|
| `URI` | `string` | Resource identifier (e.g. `file:///path`) |
| `Name` | `string` | Display name |
| `Description` | `string` | Human-readable description |
| `MimeType` | `string` | Content type |

### `Prompt`

| Field | Type | Purpose |
|---|---|---|
| `Name` | `string` | Prompt identifier |
| `Description` | `string` | Human-readable description |
| `Arguments` | `[]PromptArgument` | Typed arguments the prompt accepts |

### `PromptMessage`

| Field | Type | Purpose |
|---|---|---|
| `Role` | `string` | Message role (`user`, `assistant`, `system`) |
| `Content` | `Content` | Message content (text, image, or resource) |