multi-service mcp tool registry with dynamic tier-based loading
Exposes 90+ tools across 12 Google Workspace services (Gmail, Drive, Calendar, Docs, Sheets, Slides, Forms, Tasks, Chat, Custom Search, Contacts, Apps Script) through a unified MCP protocol interface. Uses a ToolTierLoader system defined in tool_tiers.yaml that dynamically imports tool modules based on CLI arguments (--tool-tier core/extended/complete), enabling selective capability exposure to manage API quota consumption and complexity. The tool registry is populated at server startup via dictionary mapping in main.py that conditionally imports service-specific tool modules based on configuration.
Unique: Implements a three-tier tool loading system (core/extended/complete) via YAML configuration and dynamic Python module imports, allowing operators to trade off API quota consumption against capability breadth without code changes. Most MCP servers expose a fixed tool set; this architecture enables deployment-time customization of the entire service surface.
vs alternatives: Provides finer-grained control over API quota and scope exposure than monolithic MCP servers that expose all tools unconditionally, reducing operational overhead for quota-constrained deployments.
oauth 2.0/2.1 dual-mode authentication with session persistence
Implements both OAuth 2.0 legacy flow and OAuth 2.1 with session management, selectable via CLI flag (--single-user for desktop OAuth 2.0, multi-user for OAuth 2.1 with session context). Handles credential storage via a pluggable storage backend system and manages authentication state through service-specific decorators that inject credentials into tool execution contexts. The authentication system supports both single-user desktop flows (where credentials are stored locally) and multi-user cloud deployments (where session tokens are managed server-side).
Unique: Dual-mode authentication architecture with service-specific decorator pattern (@requires_auth) that injects credentials into tool execution context, enabling both single-user desktop flows and multi-user cloud deployments from the same codebase. Separates authentication concern from tool logic via decorators rather than inline credential passing.
vs alternatives: Supports both OAuth 2.0 and 2.1 in a single deployment, whereas most MCP servers commit to one standard; the decorator-based injection pattern also decouples auth from tool logic, making it easier to add new services without credential plumbing.
google chat message sending and conversation management with thread support
Exposes tools for sending messages to Chat spaces/direct messages, retrieving message history, and managing conversations with thread support. Uses Chat API's messages.create() to send messages with optional threading (parent message ID), and messages.list() to retrieve conversation history. Supports message formatting (bold, italic, code blocks) via Chat's message formatting syntax. Handles both space messages (group conversations) and direct messages (1-on-1 conversations).
Unique: Implements thread-aware message sending via parent message ID, enabling Claude to participate in threaded conversations. Combines message creation, history retrieval, and thread management in a single tool set.
vs alternatives: Provides thread-aware messaging and conversation history retrieval in a single tool set, whereas generic Chat API clients require manual thread management; integrates message formatting for readable output.
google contacts contact management with custom fields and group organization
Provides tools for creating contacts with name, email, phone, and custom fields, organizing contacts into groups, and retrieving contact information. Uses People API's people.createContact() and people.updateContact() to manage contact data, supporting custom fields for additional metadata. Handles contact groups via contactGroups.create() and contactGroups.update(). Retrieves contacts via people.listConnections() with optional filtering by group or search query.
Unique: Implements contact group organization and custom field support, enabling Claude to create structured contact databases. Combines contact creation, group management, and retrieval in a single tool set.
vs alternatives: Provides contact group organization and custom field support in a single tool set, whereas generic People API clients require manual group management; integrates contact retrieval for downstream operations (email, calendar).
google apps script execution with custom function invocation and error handling
Exposes tools for executing Google Apps Script functions deployed as web apps or bound to Workspace documents. Uses Apps Script API's scripts.run() to invoke custom functions with parameters, returning results or error details. Supports both synchronous execution (wait for result) and asynchronous patterns (trigger and poll). Handles error reporting with stack traces and execution logs. Enables Claude to extend Workspace capabilities with custom logic without modifying the MCP server.
Unique: Implements Apps Script function invocation via the Apps Script API, enabling Claude to execute custom business logic without modifying the MCP server. Provides error handling and execution logging for debugging custom functions.
vs alternatives: Enables extensibility via Apps Script without requiring MCP server modifications, whereas monolithic MCP servers require code changes to add custom logic; supports both sync and async execution patterns for flexible workflow automation.
google custom search integration with web search and site-specific search
Exposes tools for performing web searches using Google Custom Search Engine (CSE), with support for site-specific searches and result filtering. Uses Custom Search API's cse.list() to execute searches with optional site restrictions, returning ranked results with titles, snippets, and URLs. Supports pagination for large result sets and filtering by content type (web pages, images, PDFs). Enables Claude to search the web or specific sites for information without leaving the conversation.
Unique: Integrates Google Custom Search Engine for both web-wide and site-specific searches, enabling Claude to retrieve ranked search results with snippets. Supports pagination and content type filtering for flexible search workflows.
vs alternatives: Provides site-specific search capability via Custom Search Engine configuration, whereas generic web search clients are limited to public web results; integrates result ranking and snippets for efficient information discovery.
mcp protocol transport abstraction with stdio and http server modes
Implements a transport abstraction layer that supports both stdio (for local MCP clients like Claude Desktop) and HTTP server modes (for remote clients). Uses SecureFastMCP class extending FastMCP to handle MCP protocol messages, with configurable transport via CLI flag (--transport stdio or streamable-http). The HTTP server mode exposes MCP endpoints for remote clients, while stdio mode communicates via stdin/stdout for local integration. Handles protocol serialization, message routing, and error responses transparently.
Unique: Implements dual-transport architecture (stdio and HTTP) via SecureFastMCP, allowing the same server code to run in both local and cloud deployments. Transport selection is configurable at startup via CLI flag, enabling deployment flexibility without code changes.
vs alternatives: Provides both local (stdio) and remote (HTTP) deployment modes in a single codebase, whereas most MCP servers commit to one transport; the abstraction enables seamless switching between deployment scenarios.
credential storage backend abstraction with pluggable implementations
Implements a pluggable credential storage system that abstracts the underlying storage mechanism (filesystem, database, cloud secret manager). Supports multiple backend implementations configured via environment variables or configuration files, enabling operators to choose storage based on deployment requirements. Handles credential encryption, rotation, and secure retrieval. The abstraction layer allows new storage backends to be added without modifying core authentication logic.
Unique: Implements a pluggable storage backend abstraction that decouples credential storage from authentication logic, enabling operators to choose storage based on deployment requirements. Supports multiple backend implementations (filesystem, database, cloud secret managers) via a common interface.
vs alternatives: Provides storage backend abstraction that enables flexible credential management, whereas monolithic MCP servers hardcode storage mechanisms; supports cloud secret managers for production deployments without code changes.
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