mcp-based chart generation tool registration and routing
Implements a factory pattern using @modelcontextprotocol/sdk to register 17 specialized chart generation tools as MCP-compliant endpoints. The McpServer instance manages tool discovery, input validation schemas, and request routing across multiple transport protocols (stdio, SSE, HTTP). Each tool is registered with Zod-based input schemas that enforce type safety before chart generation pipelines execute.
Unique: Uses factory pattern with McpServer class to manage 17 chart tools through a single registration point, with Zod schema validation integrated at the MCP protocol level rather than in individual tool handlers. Supports three transport protocols (stdio, SSE, HTTP) with unified session management.
vs alternatives: More modular than monolithic chart APIs because tool registration, validation, and transport are decoupled; enables AI assistants to discover and call chart tools via standard MCP protocol rather than custom REST endpoints
multi-transport protocol bridging (stdio, sse, http)
Implements three transport protocol handlers that allow the same MCP server instance to serve desktop applications (stdio), web clients (SSE with sessionId), and API services (HTTP with mcp-session-id headers). Each protocol maintains separate session maps for stateful chart generation workflows, with automatic fallback mechanisms for connection failures.
Unique: Unified MCP server that dynamically routes requests through three distinct transport protocols with separate session management per protocol, implemented via conditional handlers in src/index.ts. Session maps are protocol-specific (sessionId for SSE, mcp-session-id for HTTP, stateless for stdio).
vs alternatives: More flexible than single-protocol servers because it supports desktop (stdio), web (SSE), and API (HTTP) clients from one codebase; eliminates need for separate server instances per client type
batch chart generation with session-based state management
Manages stateful chart generation workflows across multiple requests using session maps (for SSE and HTTP protocols). Sessions maintain context across multiple chart generation calls, enabling workflows where one chart's output feeds into the next chart's input. Session state includes generated chart data, configuration history, and intermediate results.
Unique: Implements protocol-specific session maps (sessionId for SSE, mcp-session-id for HTTP) that maintain chart generation context across multiple requests. Session state is managed in src/index.ts with automatic session lifecycle handling per protocol.
vs alternatives: More stateful than stateless REST APIs because it maintains context across requests; enables iterative workflows that would require complex client-side state management in stateless architectures
zero-dependency chart rendering with local canvas execution
Renders charts entirely locally using Node.js canvas and SVG engines without external service dependencies. The rendering pipeline executes ECharts JavaScript in a Node.js context with canvas bindings, eliminating the need for browser instances, external rendering services, or cloud APIs. All rendering happens in-process with no network calls.
Unique: Implements fully self-contained chart rendering using Node.js canvas without external service calls. The rendering engine in src/utils/render.ts executes ECharts JavaScript in a Node.js context with canvas bindings, eliminating external dependencies while maintaining compatibility with the full ECharts feature set.
vs alternatives: More self-contained than services like Plotly Cloud or QuickChart because rendering happens locally; more reliable than browser-based rendering (Puppeteer) because it avoids browser process management overhead
dynamic chart configuration composition from ai-generated parameters
Accepts AI-generated chart parameters (data, styling, chart type, axes configuration) and composes them into valid ECharts option objects through a transformation pipeline. The pipeline validates inputs using Zod schemas, applies default styling, merges user-provided options with defaults, and produces complete ECharts configurations ready for rendering.
Unique: Implements configuration composition pipeline that transforms AI-generated parameters into valid ECharts options through schema validation and default merging. Each chart tool in src/tools/index.ts handles composition specific to its chart type, enabling flexible AI-driven chart generation.
vs alternatives: More flexible than fixed chart templates because it accepts dynamic parameters from AI models; more robust than direct ECharts API usage because it validates inputs and applies sensible defaults
zod-based schema validation for chart inputs
Implements type-safe input validation using Zod schemas across all 17 chart generation tools. Each tool defines a Zod schema that validates data types, array structures, numeric ranges, and required fields before the data reaches the ECharts rendering pipeline. Validation errors are caught early and returned as structured error messages to the MCP client.
Unique: Uses Zod schemas defined in src/utils/schema.ts as the single source of truth for chart input validation, integrated directly into MCP tool definitions. Validation happens at the protocol layer before tool execution, preventing invalid data from reaching the rendering engine.
vs alternatives: More robust than regex-based validation because Zod provides structural validation with type inference; catches more error classes (type mismatches, array length violations, numeric ranges) than simple presence checks
financial and trading chart generation (candlestick, ohlc, technical indicators)
Generates specialized financial charts including candlestick, OHLC (open-high-low-close), and technical indicator overlays using ECharts' financial chart components. Accepts time-series OHLC data, volume information, and technical indicator arrays (moving averages, Bollinger Bands, RSI), then transforms them into ECharts option objects with proper axis scaling, legend management, and interactive tooltips.
Unique: Implements specialized financial chart tools that handle OHLC data transformation and technical indicator overlay composition within the ECharts rendering pipeline. Uses ECharts' native financial chart components rather than custom D3 or Canvas implementations.
vs alternatives: More integrated than calling ECharts directly because it abstracts OHLC data transformation and technical indicator composition; faster than web-based charting libraries because rendering happens server-side with Node.js canvas
statistical and analytical chart generation (histograms, box plots, scatter plots)
Generates statistical visualization charts including histograms, box plots, scatter plots, and distribution curves. Accepts raw data arrays or pre-computed statistical summaries, performs binning/aggregation if needed, and renders charts with statistical annotations (quartiles, outliers, trend lines). Supports both univariate and bivariate statistical visualizations.
Unique: Provides dedicated statistical chart tools that handle data aggregation and statistical annotation rendering within ECharts. Separates statistical computation (caller's responsibility) from visualization (server's responsibility), enabling flexible statistical pipelines.
vs alternatives: More specialized than generic line/bar charts because it includes statistical annotation rendering (quartiles, outliers, trend lines); faster than Python-based statistical visualization because rendering happens in Node.js
+5 more capabilities