mcp-sdk-improvements.md•6.22 kB
# MCP SDK Implementation Improvements
## Overview
This document outlines the improvements made to the Vibe-Coder MCP server implementation to better align with the MCP TypeScript SDK best practices and improve overall code quality, maintainability, and type safety.
## Key Improvements
### 1. Tool Handler Registry
We replaced the large switch statement in the main file with a tool handler registry that maps tool names to their handler functions:
```typescript
// Before (in index.ts)
server.setRequestHandler(CallToolRequestSchema, async (request) => {
try {
switch (request.params.name) {
case "start_feature_clarification": {
// Implementation...
}
case "provide_clarification": {
// Implementation...
}
// Many more cases...
}
} catch (error) {
// Error handling...
}
});
// After
// In registry.ts
export class ToolRegistry {
private handlers: Map<string, ToolHandler> = new Map();
register<T>(name: string, handler: ToolHandler<T>): void {
this.handlers.set(name, handler);
}
async execute(name: string, params: any): Promise<any> {
const handler = this.getHandler(name);
if (!handler) {
return createToolErrorResponse(`Unknown tool "${name}"`);
}
return await handler(params);
}
}
// In index-updated.ts
server.setRequestHandler(CallToolRequestSchema, async (request) => {
try {
const toolName = request.params.name;
const toolArguments = request.params.arguments || {};
return await toolRegistry.execute(toolName, toolArguments);
} catch (error) {
// Improved error handling...
}
});
```
### 2. Robust Resource URI Handling
We implemented a robust resource URI handling mechanism using a `ResourceRegistry` class:
```typescript
// In registry.ts
export class ResourceRegistry {
private resources: ResourceRegistryEntry[] = [];
register(template: ResourceTemplate, handler: ResourceHandler): void {
this.resources.push({ template, handler });
}
findMatch(uri: string): { handler: ResourceHandler; params: Record<string, string> } | undefined {
const url = new URL(uri);
for (const { template, handler } of this.resources) {
const match = this.matchTemplate(url, template);
if (match) {
return { handler, params: match };
}
}
return undefined;
}
}
// In index-updated.ts
server.setRequestHandler(ReadResourceRequestSchema, async (request) => {
try {
const uri = request.params.uri;
const match = resourceRegistry.findMatch(uri);
if (match) {
return await match.handler(new URL(uri), match.params);
}
return createErrorResponse(ErrorCode.RESOURCE_NOT_FOUND, `Resource not found: ${uri}`);
} catch (error) {
// Improved error handling...
}
});
```
### 3. Improved Error Handling
We standardized error handling across the codebase with consistent JSON-RPC 2.0 error responses:
```typescript
// In errors.ts
export enum ErrorCode {
// JSON-RPC 2.0 Standard Error Codes
PARSE_ERROR = -32700,
INVALID_REQUEST = -32600,
METHOD_NOT_FOUND = -32601,
INVALID_PARAMS = -32602,
INTERNAL_ERROR = -32603,
// Custom Error Codes
VALIDATION_ERROR = -32000,
RESOURCE_NOT_FOUND = -32001,
// More custom error codes...
}
export const createErrorResponse = (
code: ErrorCode,
message: string,
data?: any
): ErrorResponse => {
return {
error: {
code,
message,
data
}
};
};
export const createToolErrorResponse = (
message: string,
details?: any
): ToolErrorResponse => {
return {
content: [{
type: "text",
text: `Error: ${message}`
}],
isError: true
};
};
```
### 4. Stronger Type Safety
We improved type safety throughout the codebase with Zod schemas and branded types:
```typescript
// In schemas.ts
// Branded types for IDs
export type FeatureId = string & { readonly _brand: unique symbol };
export type PhaseId = string & { readonly _brand: unique symbol };
export type TaskId = string & { readonly _brand: unique symbol };
// Zod schemas for validation
export const FeatureSchema = z.object({
id: z.string().refine(isFeatureId, "Invalid feature ID format"),
name: z.string().min(2).max(100),
// More fields...
});
// Type guards
export const isFeatureId = (id: string): id is FeatureId => id.startsWith('feature-');
// ID creators
export const createFeatureId = (id: string): FeatureId => {
if (!isFeatureId(id)) throw new Error(`Invalid feature ID format: ${id}`);
return id as FeatureId;
};
// In utils.ts
export function generateFeatureId(): FeatureId {
const randomPart = Math.random().toString(36).substring(2, 10);
return createFeatureId(`feature-${randomPart}`);
}
```
### 5. Modular Code Structure
We reorganized the codebase into more modular components with clear separation of concerns:
- `registry.ts` - Tool and resource registries
- `tool-handlers.ts` - Tool handler implementations
- `resource-handlers.ts` - Resource handler implementations
- `errors.ts` - Error handling utilities
- `schemas.ts` - Type definitions and validation schemas
## Benefits
1. **Improved Maintainability**: The modular code structure makes it easier to understand, maintain, and extend the codebase.
2. **Better Type Safety**: Branded types and Zod schemas provide stronger type checking and runtime validation.
3. **Consistent Error Handling**: Standardized error responses across the codebase with proper JSON-RPC 2.0 error codes.
4. **More Robust URI Handling**: Proper URI template matching for resources following MCP best practices.
5. **Cleaner Code**: Separation of concerns between different components and elimination of large switch statements.
## Testing
The improvements have been tested with a comprehensive test script (`test-mcp-improved.js`) that verifies the functionality of:
- Tool registration and execution
- Resource URI matching and handling
- Error reporting
- End-to-end workflows (feature clarification, PRD generation, etc.)
## Conclusion
These improvements bring the Vibe-Coder MCP server implementation more in line with MCP TypeScript SDK best practices while also improving overall code quality, maintainability, and type safety.