Google Chat MCP Sever (Extendable to Teams,Slack.)

@startuml ' Google Chat MCP - Data Flow Diagram !define SEQUENCE_DIAGRAM skinparam sequenceMessageAlign center skinparam sequenceArrowThickness 1.5 skinparam { BackgroundColor white ParticipantBackgroundColor #FEFEFE ParticipantBorderColor #999999 DatabaseBackgroundColor #ECECEC DatabaseBorderColor #666666 NoteBackgroundColor #FFF9C4 NoteBorderColor #999999 LifeLineBorderColor #CCCCCC LifeLineBackgroundColor #ECECEC } title Google Chat MCP - Data Flow Diagram ' Key actors and components actor "User" as user participant "AI Assistant" as assistant participant "MCP Client" as mcp_client participant "MCP Server" as mcp_server participant "Tool Handler" as tool_handler participant "Auth Manager" as auth_manager participant "API Client" as api_client participant "Google Chat API" as chat_api participant "People API" as people_api database "token.json" as token_file database "credentials.json" as creds_file ' ===== Phase 1: User Request Flow ===== group User Request Flow user -> assistant : 1. Natural language request\n"Send a message to my team" activate assistant assistant -> mcp_client : 2. Resolve to tool call activate mcp_client note right of assistant AI identifies intent and parameters: - Tool: mcp_google_chat_send_message_tool - space_name: "spaces/AAQAXL5fJxI" - text: "Hello team, meeting at 3pm" end note mcp_client -> mcp_server : 3. JSON-RPC request activate mcp_server note right of mcp_client { "jsonrpc": "2.0", "method": "mcp_google_chat_send_message_tool", "params": { "space_name": "spaces/AAQAXL5fJxI", "text": "Hello team, meeting at 3pm" }, "id": "call-1234" } end note end ' ===== Phase 2: Authentication Flow ===== group Authentication Flow mcp_server -> tool_handler : 4. Forward to tool implementation activate tool_handler tool_handler -> auth_manager : 5. Request credentials activate auth_manager auth_manager -> token_file : 6. Read stored OAuth token activate token_file token_file --> auth_manager : Return token data deactivate token_file alt Token is expired auth_manager -> creds_file : 7a. Read client credentials activate creds_file creds_file --> auth_manager : Return client ID/secret deactivate creds_file auth_manager -> auth_manager : 8a. Request token refresh note right of auth_manager POST https://oauth2.googleapis.com/token grant_type=refresh_token refresh_token=[stored refresh token] client_id=[client ID] client_secret=[client secret] end note auth_manager -> token_file : 9a. Update stored token end auth_manager --> tool_handler : 7. Return valid credentials deactivate auth_manager end ' ===== Phase 3: API Interaction ===== group API Interaction tool_handler -> api_client : 8. Call Chat API activate api_client api_client -> chat_api : 9. Send API request with auth token activate chat_api note right of api_client POST https://chat.googleapis.com/v1/spaces/{spaceName}/messages Authorization: Bearer ya29.a0... { "text": "Hello team, meeting at 3pm" } end note chat_api --> api_client : 10. Return API response deactivate chat_api note right of chat_api { "name": "spaces/AAQAXL5fJxI/messages/ABCDEF123", "sender": { "name": "users/12345", "displayName": "AI Assistant", "avatarUrl": "..." }, "text": "Hello team, meeting at 3pm", "createTime": "2023-05-10T10:15:30Z" } end note api_client --> tool_handler : 11. Return API result deactivate api_client end ' ===== Phase 4: Response Flow ===== group Response Flow tool_handler --> mcp_server : 12. Return formatted result deactivate tool_handler mcp_server --> mcp_client : 13. JSON-RPC response deactivate mcp_server note left of mcp_server { "jsonrpc": "2.0", "result": { "name": "spaces/AAQAXL5fJxI/messages/ABCDEF123", "text": "Hello team, meeting at 3pm", "createTime": "2023-05-10T10:15:30Z" }, "id": "call-1234" } end note mcp_client --> assistant : 14. Return structured result deactivate mcp_client assistant --> user : 15. Natural language response\n"I've sent your message to the team" deactivate assistant end ' ===== Alternative Flow Example ===== note across: Alternative flow for getting user information group User Info Flow (Alternative) participant "User Info Tool" as user_tool api_client -> people_api : A1. Request user profile activate people_api note right of api_client GET https://people.googleapis.com/v1/people/me Authorization: Bearer ya29.a0... end note people_api --> api_client : A2. Return user profile data deactivate people_api note right of people_api { "names": [{ "displayName": "John Doe", "givenName": "John", "familyName": "Doe" }], "emailAddresses": [{ "value": "john.doe@example.com" }] } end note end @enduml