# Requirements Document
## Introduction
The AWS Billing MCP Server is a Model Context Protocol (MCP) server optimized for Claude Desktop personal use. It provides comprehensive tools to analyze AWS billing data through natural language queries. The system uses environment variables for AWS credentials (no database storage) and communicates via MCP's stdio protocol for seamless Claude Desktop integration.
## Glossary
- **MCP Server**: A Model Context Protocol server that exposes tools and resources to LLM clients
- **AWS Billing Data**: Cost and usage information from AWS Cost Explorer and Billing APIs
- **LLM Agent**: A language model client that connects to the MCP server to access billing tools
- **Google SSO**: Google Single Sign-On authentication system
- **Cost Explorer**: AWS service providing cost and usage analytics
- **Billing Query**: Natural language questions about AWS costs, usage patterns, or billing anomalies
## Requirements
### Requirement 1 - Simplified Credential Handling
**User Story:** As a Claude Desktop user, I want to configure AWS credentials directly in my Claude Desktop configuration, so that the server can access billing data without complex credential storage.
#### Acceptance Criteria
1. WHEN AWS credentials are provided via environment variables, THE AWS_Billing_MCP_Server SHALL read them directly from the Claude Desktop configuration
2. WHEN valid AWS credentials are configured, THE AWS_Billing_MCP_Server SHALL establish secure connection to AWS Cost Explorer APIs
3. WHEN invalid or missing AWS credentials are provided, THE AWS_Billing_MCP_Server SHALL gracefully fall back to mock data for testing
4. WHEN AWS credentials are used, THE AWS_Billing_MCP_Server SHALL NOT store them in any database or encrypted storage
5. WHERE no AWS credentials are provided, THE AWS_Billing_MCP_Server SHALL automatically use mock billing data for demonstration purposes
### Requirement 2
**User Story:** As a system administrator, I want the MCP server to retrieve and cache AWS billing data, so that LLM agents can access current and historical cost information efficiently.
#### Acceptance Criteria
1. WHEN the server starts, THE AWS_Billing_MCP_Server SHALL fetch billing data from AWS Cost Explorer for the last 12 months
2. WHEN billing data is retrieved, THE AWS_Billing_MCP_Server SHALL parse and structure cost information by service, region, and time period
3. WHEN billing data retrieval fails, THE AWS_Billing_MCP_Server SHALL log errors and retry with exponential backoff
4. WHILE the server is running, THE AWS_Billing_MCP_Server SHALL refresh billing data every 24 hours automatically
5. WHEN billing data is cached, THE AWS_Billing_MCP_Server SHALL store data in a queryable format for efficient analysis
### Requirement 3
**User Story:** As an LLM agent, I want to access MCP tools for billing analysis, so that I can answer natural language queries about AWS costs and usage patterns.
#### Acceptance Criteria
1. WHEN an LLM agent connects to the server, THE AWS_Billing_MCP_Server SHALL expose tools for cost analysis, usage comparison, and trend identification
2. WHEN a cost analysis tool is invoked, THE AWS_Billing_MCP_Server SHALL return structured data about costs filtered by service, time period, or region
3. WHEN a usage comparison tool is invoked, THE AWS_Billing_MCP_Server SHALL calculate and return percentage changes between specified time periods
4. WHEN a trend analysis tool is invoked, THE AWS_Billing_MCP_Server SHALL identify cost patterns and anomalies in the billing data
5. WHEN billing anomaly detection is requested, THE AWS_Billing_MCP_Server SHALL compare current costs against historical baselines and flag significant deviations
### Requirement 4 - Simplified Authentication
**User Story:** As a Claude Desktop user, I want the server to work without complex authentication, so that I can use it seamlessly for personal AWS billing analysis.
#### Acceptance Criteria
1. WHEN used with Claude Desktop, THE AWS_Billing_MCP_Server SHALL operate with authentication disabled by default
2. WHEN authentication is disabled, THE AWS_Billing_MCP_Server SHALL communicate directly via MCP stdio protocol
3. WHEN Google SSO is needed for enterprise use, THE AWS_Billing_MCP_Server SHALL support optional authentication via environment variable configuration
4. WHEN running in personal mode, THE AWS_Billing_MCP_Server SHALL NOT require any authentication setup
5. WHERE security is needed, THE AWS_Billing_MCP_Server SHALL rely on Claude Desktop's own security model
### Requirement 5
**User Story:** As an LLM agent, I want to query billing data using natural language parameters, so that I can provide contextual answers about AWS costs.
#### Acceptance Criteria
1. WHEN a billing query specifies a time period, THE AWS_Billing_MCP_Server SHALL filter data to match the requested date range
2. WHEN a billing query specifies AWS services, THE AWS_Billing_MCP_Server SHALL return costs aggregated by the specified services
3. WHEN a billing query requests cost comparisons, THE AWS_Billing_MCP_Server SHALL calculate differences between specified periods or services
4. WHEN a billing query asks for top cost drivers, THE AWS_Billing_MCP_Server SHALL rank services or resources by cost contribution
5. WHEN billing data is returned, THE AWS_Billing_MCP_Server SHALL format responses in structured JSON suitable for LLM processing
### Requirement 6
**User Story:** As a system administrator, I want the MCP server to handle errors gracefully, so that the system remains stable and provides useful feedback when issues occur.
#### Acceptance Criteria
1. WHEN AWS API rate limits are exceeded, THE AWS_Billing_MCP_Server SHALL implement exponential backoff and retry logic
2. WHEN network connectivity to AWS fails, THE AWS_Billing_MCP_Server SHALL serve cached data and log connectivity issues
3. WHEN invalid tool parameters are provided, THE AWS_Billing_MCP_Server SHALL return descriptive error messages without exposing sensitive information
4. WHEN system resources are low, THE AWS_Billing_MCP_Server SHALL prioritize critical operations and log resource warnings
5. WHEN authentication failures occur, THE AWS_Billing_MCP_Server SHALL log security events and provide appropriate error responses
### Requirement 7 - Simplified Logging and Monitoring
**User Story:** As a Claude Desktop user, I want the MCP server to provide clear logging without unnecessary complexity, so that I can troubleshoot issues easily.
#### Acceptance Criteria
1. WHEN the server processes requests, THE AWS_Billing_MCP_Server SHALL log essential information without interfering with MCP protocol
2. WHEN errors occur, THE AWS_Billing_MCP_Server SHALL log detailed error information to stderr (not stdout to avoid MCP interference)
3. WHEN AWS API calls are made, THE AWS_Billing_MCP_Server SHALL log API request metadata for debugging
4. WHEN running in MCP mode, THE AWS_Billing_MCP_Server SHALL NOT output console logs that interfere with JSON protocol
5. WHERE Claude Desktop integration is used, THE AWS_Billing_MCP_Server SHALL NOT require HTTP health check endpoints
### Requirement 8 - Claude Desktop Optimization
**User Story:** As a Claude Desktop user, I want the MCP server to be optimized for personal use, so that it works seamlessly without enterprise complexity.
#### Acceptance Criteria
1. WHEN starting up, THE AWS_Billing_MCP_Server SHALL NOT create HTTP endpoints that could cause port conflicts
2. WHEN communicating with Claude, THE AWS_Billing_MCP_Server SHALL use pure MCP stdio protocol
3. WHEN no real AWS credentials are provided, THE AWS_Billing_MCP_Server SHALL automatically provide mock data for testing
4. WHEN configured for Claude Desktop, THE AWS_Billing_MCP_Server SHALL minimize resource usage and startup time
5. WHERE simplicity is prioritized, THE AWS_Billing_MCP_Server SHALL avoid unnecessary enterprise features like multi-tenancy
