Zerion MCP Server

## ADDED Requirements ### Requirement: MCP Server Initialization The system SHALL initialize a FastMCP server that exposes Zerion API operations as MCP tools. #### Scenario: Successful initialization - **WHEN** the server starts with valid configuration - **THEN** FastMCP server is created from OpenAPI spec - **AND** HTTP client is configured with base URL and headers - **AND** server is ready to accept MCP requests #### Scenario: Missing API key - **WHEN** ZERION_API_KEY environment variable is not set - **THEN** server SHALL print error message with setup instructions - **AND** server SHALL exit gracefully without starting ### Requirement: OpenAPI Specification Loading The system SHALL fetch and parse the Zerion OpenAPI specification at runtime. #### Scenario: Successful spec loading - **WHEN** server initializes - **THEN** OpenAPI spec is fetched from configured URL - **AND** YAML content is parsed into Python dictionary - **AND** spec is validated by FastMCP #### Scenario: Network failure during spec load - **WHEN** OpenAPI spec URL is unreachable - **THEN** server SHALL log the error with URL details - **AND** server SHALL exit with clear error message ### Requirement: HTTP Client Configuration The system SHALL configure an async HTTP client with proper authentication headers. #### Scenario: Client setup with API key - **WHEN** server initializes with valid ZERION_API_KEY - **THEN** httpx.AsyncClient is created - **AND** Authorization header is set to API key value - **AND** base_url is set to Zerion API endpoint ### Requirement: MCP Tool Generation The system SHALL auto-generate MCP tools from OpenAPI operations. #### Scenario: Route mapping - **WHEN** FastMCP processes OpenAPI spec - **THEN** each API endpoint becomes an MCP tool - **AND** tools are registered with MCPType.TOOL - **AND** parameter schemas match OpenAPI definitions ### Requirement: Server Execution The system SHALL run the MCP server and handle requests. #### Scenario: Server running - **WHEN** mcp.run() is called - **THEN** server listens for MCP protocol messages - **AND** tool invocations are routed to Zerion API - **AND** responses are returned via MCP protocol