feat: MCP best practices 적용 - tool annotations, server instructions, error codes

- 모든 도구에 annotations 추가 (readOnlyHint, destructiveHint, idempotentHint, openWorldHint)
- Server instructions 추가 (워크플로우 안내)
- McpError + ErrorCode로 파라미터 검증 및 에러 처리 개선
- server-card.json에 annotations, capabilities, 상세 설명 추가

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

mcp/src/index.ts

@@ -56,20 +56,27 @@ async function startHttp(server: ReturnType<typeof createServer>, port: number)
     res.json({
       serverInfo: { name: "web-inspector-mcp", version: "1.0.0" },
       authentication: { required: false },
+      capabilities: {
+        tools: true,
+        resources: false,
+        prompts: false,
+      },
       tools: [
         {
           name: "inspect_page",
           description:
-            "Inspect a single web page for HTML/CSS quality, accessibility (WCAG/KWCAG), SEO, and performance/security. Returns scores, grades, and top issues.",
+            "Inspect a single web page for HTML/CSS quality, accessibility (WCAG/KWCAG), SEO, and performance/security. Returns scores, grades, and top issues. Takes 10-30 seconds.",
+          annotations: { title: "Inspect Page", readOnlyHint: true, destructiveHint: false, idempotentHint: true, openWorldHint: true },
           inputSchema: {
             type: "object",
             properties: {
-              url: { type: "string", description: "URL to inspect" },
+              url: { type: "string", description: "The URL of the web page to inspect (must start with http:// or https://)" },
               accessibility_standard: {
                 type: "string",
                 enum: ["wcag_2.0_a", "wcag_2.0_aa", "wcag_2.1_aa", "wcag_2.2_aa", "kwcag_2.1", "kwcag_2.2"],
+                description: "Accessibility standard to check against (default: wcag_2.1_aa)",
               },
-              language: { type: "string", enum: ["en", "ko"] },
+              language: { type: "string", enum: ["en", "ko"], description: "Response language: 'en' for English, 'ko' for Korean" },
             },
             required: ["url"],
           },
@@ -77,52 +84,64 @@ async function startHttp(server: ReturnType<typeof createServer>, port: number)
         {
           name: "inspect_site",
           description:
-            "Start a site-wide crawl and inspection. Returns a site_inspection_id for tracking.",
+            "Start a site-wide crawl and inspection. Crawls links from the root URL and inspects each page. Returns a site_inspection_id for tracking. Use get_inspection to check results later.",
+          annotations: { title: "Inspect Site", readOnlyHint: true, destructiveHint: false, idempotentHint: false, openWorldHint: true },
           inputSchema: {
             type: "object",
             properties: {
-              url: { type: "string" },
+              url: { type: "string", description: "Root URL of the site to crawl and inspect" },
-              max_pages: { type: "number" },
+              max_pages: { type: "number", description: "Maximum number of pages to crawl (default: 20, max: 500, 0: unlimited)" },
-              max_depth: { type: "number" },
+              max_depth: { type: "number", description: "Maximum link depth to crawl (default: 2, max: 3)" },
-              language: { type: "string", enum: ["en", "ko"] },
+              accessibility_standard: {
+                type: "string",
+                enum: ["wcag_2.0_a", "wcag_2.0_aa", "wcag_2.1_aa", "wcag_2.2_aa", "kwcag_2.1", "kwcag_2.2"],
+                description: "Accessibility standard to check against (default: wcag_2.1_aa)",
+              },
+              language: { type: "string", enum: ["en", "ko"], description: "Response language: 'en' for English, 'ko' for Korean" },
             },
             required: ["url"],
           },
         },
         {
           name: "get_inspection",
-          description: "Get detailed inspection results by ID.",
+          description: "Get detailed inspection results by inspection ID. Works for both single-page and site inspections.",
+          annotations: { title: "Get Inspection", readOnlyHint: true, destructiveHint: false, idempotentHint: true, openWorldHint: false },
           inputSchema: {
             type: "object",
-            properties: { id: { type: "string" }, language: { type: "string", enum: ["en", "ko"] } },
+            properties: {
+              id: { type: "string", description: "The inspection_id or site_inspection_id to retrieve" },
+              language: { type: "string", enum: ["en", "ko"], description: "Response language: 'en' for English, 'ko' for Korean" },
+            },
             required: ["id"],
           },
         },
         {
           name: "get_issues",
           description:
-            "Get filtered issues for single-page or site inspections.",
+            "Get a filtered list of issues found during an inspection. Works with both single-page inspection_id and site_inspection_id. For site inspections, aggregates issues from all pages.",
+          annotations: { title: "Get Issues", readOnlyHint: true, destructiveHint: false, idempotentHint: true, openWorldHint: false },
           inputSchema: {
             type: "object",
             properties: {
-              id: { type: "string" },
+              id: { type: "string", description: "The inspection_id or site_inspection_id to get issues for" },
-              category: { type: "string" },
+              category: { type: "string", enum: ["html_css", "accessibility", "seo", "performance_security"], description: "Filter by category" },
-              severity: { type: "string" },
+              severity: { type: "string", enum: ["critical", "major", "minor", "info"], description: "Filter by severity" },
-              page_url: { type: "string" },
+              page_url: { type: "string", description: "For site inspections: filter issues by page URL substring" },
-              language: { type: "string", enum: ["en", "ko"] },
+              language: { type: "string", enum: ["en", "ko"], description: "Response language: 'en' for English, 'ko' for Korean" },
             },
             required: ["id"],
           },
         },
         {
           name: "get_history",
-          description: "List recent inspection history.",
+          description: "List recent inspection history. Optionally filter by URL substring.",
+          annotations: { title: "Get History", readOnlyHint: true, destructiveHint: false, idempotentHint: true, openWorldHint: false },
           inputSchema: {
             type: "object",
             properties: {
-              url: { type: "string" },
+              url: { type: "string", description: "Optional URL substring to filter results" },
-              limit: { type: "number" },
+              limit: { type: "number", description: "Number of results to return (default: 10)" },
-              language: { type: "string", enum: ["en", "ko"] },
+              language: { type: "string", enum: ["en", "ko"], description: "Response language: 'en' for English, 'ko' for Korean" },
             },
           },
         },

mcp/src/server.ts

@@ -1,7 +1,9 @@
 import { Server } from "@modelcontextprotocol/sdk/server/index.js";
 import {
   CallToolRequestSchema,
+  ErrorCode,
   ListToolsRequestSchema,
+  McpError,
 } from "@modelcontextprotocol/sdk/types.js";
 import { ApiClient } from "./api-client.js";
 import { t } from "./i18n/index.js";
@@ -27,7 +29,18 @@ export function createServer(apiUrl: string, defaultLang: Lang): Server {
 
   const server = new Server(
     { name: "web-inspector-mcp", version: "1.0.0" },
-    { capabilities: { tools: {} } },
+    {
+      capabilities: { tools: {} },
+      instructions:
+        "Web Inspector MCP server analyzes web pages and websites for HTML/CSS quality, accessibility (WCAG 2.x / KWCAG 2.x), SEO, and performance/security.\n\n" +
+        "Typical workflow:\n" +
+        "1. Use `inspect_page` to audit a single URL (takes 10-30s, returns scores and top issues).\n" +
+        "2. Use `inspect_site` to start a site-wide crawl (returns an ID immediately; the crawl runs in background).\n" +
+        "3. Use `get_inspection` to retrieve detailed results by ID.\n" +
+        "4. Use `get_issues` to filter and drill into specific issues by category or severity.\n" +
+        "5. Use `get_history` to review past inspections.\n\n" +
+        "All tools accept a `language` parameter ('en' or 'ko') to control the response language.",
+    },
   );
 
   // ── List tools ──────────────────────────────────────────
@@ -37,6 +50,13 @@ export function createServer(apiUrl: string, defaultLang: Lang): Server {
       {
         name: "inspect_page",
         description: t("inspect_page.description", defaultLang),
+        annotations: {
+          title: "Inspect Page",
+          readOnlyHint: true,
+          destructiveHint: false,
+          idempotentHint: true,
+          openWorldHint: true,
+        },
         inputSchema: {
           type: "object" as const,
           properties: {
@@ -61,6 +81,13 @@ export function createServer(apiUrl: string, defaultLang: Lang): Server {
       {
         name: "inspect_site",
         description: t("inspect_site.description", defaultLang),
+        annotations: {
+          title: "Inspect Site",
+          readOnlyHint: true,
+          destructiveHint: false,
+          idempotentHint: false,
+          openWorldHint: true,
+        },
         inputSchema: {
           type: "object" as const,
           properties: {
@@ -93,6 +120,13 @@ export function createServer(apiUrl: string, defaultLang: Lang): Server {
       {
         name: "get_inspection",
         description: t("get_inspection.description", defaultLang),
+        annotations: {
+          title: "Get Inspection",
+          readOnlyHint: true,
+          destructiveHint: false,
+          idempotentHint: true,
+          openWorldHint: false,
+        },
         inputSchema: {
           type: "object" as const,
           properties: {
@@ -112,6 +146,13 @@ export function createServer(apiUrl: string, defaultLang: Lang): Server {
       {
         name: "get_issues",
         description: t("get_issues.description", defaultLang),
+        annotations: {
+          title: "Get Issues",
+          readOnlyHint: true,
+          destructiveHint: false,
+          idempotentHint: true,
+          openWorldHint: false,
+        },
         inputSchema: {
           type: "object" as const,
           properties: {
@@ -150,6 +191,13 @@ export function createServer(apiUrl: string, defaultLang: Lang): Server {
       {
         name: "get_history",
         description: t("get_history.description", defaultLang),
+        annotations: {
+          title: "Get History",
+          readOnlyHint: true,
+          destructiveHint: false,
+          idempotentHint: true,
+          openWorldHint: false,
+        },
         inputSchema: {
           type: "object" as const,
           properties: {
@@ -178,6 +226,14 @@ export function createServer(apiUrl: string, defaultLang: Lang): Server {
     const { name, arguments: args = {} } = request.params;
     const lang: Lang = (args.language as Lang) || defaultLang;
 
+    // Validate required params
+    if ((name === "inspect_page" || name === "inspect_site") && !args.url) {
+      throw new McpError(ErrorCode.InvalidParams, "Missing required parameter: url");
+    }
+    if ((name === "get_inspection" || name === "get_issues") && !args.id) {
+      throw new McpError(ErrorCode.InvalidParams, "Missing required parameter: id");
+    }
+
     try {
       let text: string;
 
@@ -227,14 +283,12 @@ export function createServer(apiUrl: string, defaultLang: Lang): Server {
           break;
 
         default:
-          return {
+          throw new McpError(ErrorCode.MethodNotFound, `Unknown tool: ${name}`);
-            content: [{ type: "text", text: `Unknown tool: ${name}` }],
-            isError: true,
-          };
       }
 
       return { content: [{ type: "text", text }] };
     } catch (error) {
+      if (error instanceof McpError) throw error;
       const message = error instanceof Error ? error.message : String(error);
       return {
         content: [{ type: "text", text: `Error: ${message}` }],