MCPApp

MCPApp is an MCP server and network framework that enables AI applications to access Google Workspace data and external services directly via Google Apps Script. Designed for developers building automation workflows, script-based agents, and enterprise integrations, the project allows developers to expose Google Workspace services such as Gmail and Google Calendar to Model Context Protocol clients. Users can deploy MCPApp either as an independent MCP server that handles incoming JSON-RPC requests via Web Apps or as a client that orchestrates multiple downstream MCP servers within Google Apps Script. MCPApp supports standard Model Context Protocol methods, including initialization, tool discovery, prompt retrieval, and tool execution. Developers can also integrate MCPApp with the Google Apps Script Agent Development Kit to coordinate multi-agent systems and implement pre-tool or post-tool execution hooks. The library includes built-in Google Sheets logging for request auditing, lock handling through Google Apps Script LockService to manage concurrency, and access key validation to protect custom script endpoints.

Category: Communication & Messaging

Tags: gmail, google-apps-script, google-calendar, google-workspace

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How to install and configure MCPApp

1. Open your Google Apps Script project and import the MCPApp library or source files into the editor. 2. Instantiate the server in your script by calling return new MCPApp.mcpApp({ accessKey: "your-access-key" }), configuring custom tool functions and optional LockService settings. 3. Deploy the Google Apps Script project as a Web App to obtain a public HTTP endpoint URL. 4. Test your deployment using curl commands by sending JSON-RPC 2.0 payloads for initialize, tools/list, and tools/call to your Web App URL. 5. Register the Web App URL and header credentials inside your client configuration, such as Gemini CLI or another compatible HTTP MCP client, as documented in the MCPApp repository (https://github.com/tanaikech/MCPApp).

What you can do with MCPApp

• Query and triage Gmail messages directly from AI clients by calling custom Google Apps Script tools exposed through the MCPApp server interface. - Schedule, update, and manage Google Calendar events using standardized MCP tool calls invoked by Gemini CLI or conversational assistants. - Orchestrate distributed MCP networks across multiple remote HTTP endpoints directly from inside a central Google Apps Script automation environment. - Record detailed JSON-RPC request and response telemetry in designated Google Sheets spreadsheets for audit logging and performance debugging. - Implement custom pre-tool and post-tool lifecycle hooks via GasHookManager to validate parameters before executing Google Workspace actions.

Key facts

• https://github.com/tanaikech/MCPApp
• Communication & Messaging, CRM, ERP & E-commerce
• gmail, google-apps-script, google-calendar, google-workspace

Part of MCP Servers

What can MCPApp do?

MCPApp allows developers to turn Google Apps Script into a Model Context Protocol server or client. It exposes Google Workspace capabilities such as Gmail and Google Calendar to AI assistants like Gemini CLI. It also manages request locking via LockService, validates requests using access keys, and logs operations directly into Google Sheets.

How do I configure MCPApp in Google Apps Script?

You configure MCPApp by importing the library into your Google Apps Script project and instantiating it with your desired options, such as an access key and concurrency locks. Once deployed as a public or authenticated Web App, the generated URL receives JSON-RPC 2.0 requests from remote MCP clients.

Which MCP clients work with MCPApp?

MCPApp works with HTTP-based Model Context Protocol clients that support custom Web App endpoints, including Gemini CLI and custom agents. Because it implements standard JSON-RPC 2.0 methods such as initialize, tools/list, and tools/call, any client capable of posting to web endpoints can interact with the server.

Is MCPApp open source?

Yes, MCPApp is open-source software licensed under the MIT License. The complete source code, documentation, and example curl commands are hosted on GitHub, allowing developers to inspect, modify, and deploy the Google Apps Script implementation freely for personal and commercial projects.