# MCP Protocol Implementation Plan
## Overview
This document outlines the implementation plan for the Model Communication Protocol (MCP) STDIO interface that will allow our CalDAV application to communicate with MCP clients.
## MCP Protocol Basics
The MCP protocol uses STDIO (standard input/output) for communication between the client and server. Messages are sent as JSON objects over standard input, and responses are sent as JSON objects over standard output.
## Message Format
### Request Format
```json
{
"jsonrpc": "2.0",
"id": "unique-request-id",
"method": "method-name",
"params": {
"param1": "value1",
"param2": "value2"
}
}
```
### Response Format
```json
{
"jsonrpc": "2.0",
"id": "unique-request-id",
"result": {
"data": "response-data"
}
}
```
### Error Response Format
```json
{
"jsonrpc": "2.0",
"id": "unique-request-id",
"error": {
"code": 1001,
"message": "Error description"
}
}
```
## Required Methods
### 1. Event Operations
- `caldav.event.create`: Create a new event
- `caldav.event.read`: Read an existing event
- `caldav.event.update`: Update an existing event
- `caldav.event.delete`: Delete an event
### 2. Journal Operations
- `caldav.journal.create`: Create a new journal entry
- `caldav.journal.read`: Read an existing journal entry
- `caldav.journal.update`: Update an existing journal entry
- `caldav.journal.delete`: Delete a journal entry
### 3. Todo Operations
- `caldav.todo.create`: Create a new todo item
- `caldav.todo.read`: Read an existing todo item
- `caldav.todo.update`: Update an existing todo item
- `caldav.todo.delete`: Delete a todo item
### 4. List Operations
- `caldav.event.list`: List all events
- `caldav.journal.list`: List all journal entries
- `caldav.todo.list`: List all todo items
## Implementation Approach
### STDIO Interface Components
1. **Message Parser**: Parse incoming JSON messages from STDIO
2. **Command Router**: Route commands to appropriate handlers
3. **Response Formatter**: Format responses according to MCP protocol
4. **Error Handler**: Handle and format errors properly
### Message Flow Diagram
```mermaid
graph LR
A[STDIO Input] --> B[Message Parser]
B --> C[Command Router]
C --> D[Operation Handler]
D --> E[Response Formatter]
E --> F[STDIO Output]
C --> G[Error Handler]
G --> H[Error Response Formatter]
H --> F
```
## Data Structures for Operations
### Event Operations
- **Create**: Accepts event properties, returns created event with ID
- **Read**: Accepts event ID, returns event data
- **Update**: Accepts event ID and updated properties, returns updated event
- **Delete**: Accepts event ID, returns confirmation
### Journal Operations
- **Create**: Accepts journal properties, returns created journal with ID
- **Read**: Accepts journal ID, returns journal data
- **Update**: Accepts journal ID and updated properties, returns updated journal
- **Delete**: Accepts journal ID, returns confirmation
### Todo Operations
- **Create**: Accepts todo properties, returns created todo with ID
- **Read**: Accepts todo ID, returns todo data
- **Update**: Accepts todo ID and updated properties, returns updated todo
- **Delete**: Accepts todo ID, returns confirmation
## Error Handling
### Standard Error Codes
- `1001`: Invalid parameters
- `1002`: Resource not found
- `1003`: Authentication failed
- `1004`: Internal server error
- `1005`: Operation not supported
### Error Response Structure
```json
{
"jsonrpc": "2.0",
"id": "request-id",
"error": {
"code": 1001,
"message": "Error description",
"data": {
"field": "invalid-field-name"
}
}
}
```
## Configuration Requirements
The application should support configuration through:
- Environment variables
- Configuration file (JSON format)
- Command-line arguments
## Testing Considerations
- Unit tests for each operation method
- Integration tests for STDIO interface
- End-to-end tests with mock CalDAV server
- Error condition testing
