AppDog

Compose and generate effortlessly async API clients and MCP servers from any OpenAPI specifications.

For Windows users, MCP Install command needs a manual edit of the generated Claude configuration. See this issue for more details.

Overview

AppDog is a Python package that simplifies working with OpenAPI-based APIs by:

• Automatically generating fully typed Python clients from OpenAPI specifications
• Creating ready-to-use MCP (Model Context Protocol) servers for API integrations
• Managing multiple API clients in a single project with version locking
• Providing a simple CLI for adding, removing, managing API clients, and installing MCP servers

Installation

uv add appdog

Quick Start

Initialize a project

# Create a new project in the current directory
appdog init

# Or specify a project directory
appdog init --project /path/to/project

Add an API client

# Add a new API client from an OpenAPI spec URL or file
appdog add petstore --uri https://petstore3.swagger.io/api/v3/openapi.json

List and show available APIs

# List all API clients in the project
appdog list

# Show details for a specific API client
appdog show petstore

Upgrade API clients

# Sync API clients with the project registry
appdog sync --upgrade

# Lock API clients
appdog lock --upgrade

Generate an MCP server

# Generate and install an MCP server with all registered APIs
appdog mcp install -n "My API Server"

# Or run the server directly
appdog mcp run -n "My API Server"

# Or run in development mode with inspector
appdog mcp dev -n "My API Server"

Project Structure

After initializing a project and adding APIs, your project will have:

project/
├── apps.yaml     # Installed API appdog settings (auto-generated)
├── apps.lock     # Lock file with app specs and hashes (auto-generated)
└── ...           # Project files

Using Generated Clients

After adding an API client, you can import and use it in your code:

# Import generated client
import appdog.petstore

# Use the client
async def main() -> None:
    async with appdog.petstore.client as client:
        pets = await client.get_pet_find_by_status(status='available')
        print(pets)

And compose your own MCP server:

import appdog.petstore
from fastmcp import FastMCP

mcp = FastMCP()

@mcp.tool()
async def hello_petstore() -> str:
    async with appdog.petstore.client as client:
        pets = await client.get_pet_find_by_status(status='available')
        return pets

Environment Variables

API credentials can be configured using environment variables:

APPDOG_<CLIENT_NAME>_TOKEN=your_token
APPDOG_<CLIENT_NAME>_API_KEY=your_api_key

MCP Integration

The package includes full support for MCP server generation:

1. Generate an MCP server file:

   appdog mcp install -n "My API Server"
   

2. Use with FastMCP or other MCP clients:

   from appdog import Project
   from fastmcp import FastMCP
   
   mcp = FastMCP()
   
   project = Project.load(project_dir=PROJECT_DIR)
   project.mount(mcp)
   

CLI Usage

Global Options

• --verbose, -v: Enable verbose output
• --debug, -d: Enable all debug logs, including dependencies
• --project, -p: Specify project directory (defaults to current directory)

Commands

Show CLI version

appdog version

Initialize Project

appdog init [--force] [--project PATH]

• --force: Force initialization even if config already exists

Add API Client

appdog add NAME --uri URI [--base-url URL] [OPTIONS]

• NAME: Application name
• --uri: OpenAPI specification URL or file path
• --base-url: Base URL for API calls
• --include-methods: Methods to include
• --exclude-methods: Methods to exclude
• --include-tags: Tags to include
• --exclude-tags: Tags to exclude
• --force: Overwrite application if it already exists with a different URI
• --frozen: Skip adding application specification in project lock file
• --upgrade: Force upgrading application specification
• --sync: Sync application specification with project registry

Remove API Client

appdog remove NAME [OPTIONS]

• NAME: Application name
• --frozen: Skip removing application specification from project lock file
• --sync: Sync application removal with project registry

List API Clients

appdog list [--project PATH]

Show API Client Details

appdog show NAME [--project PATH]

• NAME: Application name

Lock API Specifications

appdog lock [OPTIONS]

• --force: Overwrite application if it exists with a different URI
• --upgrade: Overwrite application specification with a different URI

Sync API Clients

appdog sync [OPTIONS]

• --force: Overwrite application if it exists with a different URI
• --frozen: Skip updating application specification in project lock file
• --upgrade: Force upgrading application specification

Generate MCP Server

appdog mcp [COMMAND] [OPTIONS]

Commands:

• install: Install applications in MCP client
• run: Run MCP applications in production mode
• dev: Run MCP applications in development mode with inspector

Each command supports specific options:

Common Options (all commands)

• --name, -n: Name of the MCP server (default: "AppDog MCP Server")
• --force: Overwrite server file if it exists
• --project, -p: Project directory (defaults to current)
• --output, -o: Output path for MCP server file

Install Command

appdog mcp install [OPTIONS]

• --env-var, -v: Environment variables in KEY=VALUE format
• --env-file, -f: Environment file with KEY=VALUE pairs
• --with: Additional packages to install in dev mode
• --with-editable, -e: Local packages to install in editable mode

Run Command

appdog mcp run [OPTIONS]

• --transport, -t: Transport to use for MCP run (stdio or sse)

Dev Command

appdog mcp dev [OPTIONS]

• --with: Additional packages to install in dev mode
• --with-editable, -e: Local packages to install in editable mode

Advanced Usage

Client Configuration

Create a custom apps.yaml to configure your API clients:

petstore:
  uri: https://petstore3.swagger.io/api/v3/openapi.json
  base_url: https://petstore3.swagger.io/api/v3
  include_tags:
    - pet
    - store

Custom Authentication

For MCP usage, see environment variables section

Create a client with custom authentication:

from appdog.petstore import PetstoreClient

# Custom API key
client = PetstoreClient(api_key="YOUR_API_KEY")

# Custom headers
client = PetstoreClient(
    headers={"Authorization": "Bearer YOUR_TOKEN"}
)

Contributing

See CONTRIBUTING.md for information on contributing to the project.

License

This project is licensed under the MIT License - see the LICENSE file for details.