feat: improve error handling and response types for library search and documentation fetch

src/index.ts

@@ -5,6 +5,7 @@ import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js"
 import { z } from "zod";
 import { searchLibraries, fetchLibraryDocumentation } from "./lib/api.js";
 import { formatSearchResults } from "./lib/utils.js";
+import { SearchResponse } from "./lib/types.js";
 import dotenv from "dotenv";
 import { createServer } from "http";
 import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
@@ -70,25 +71,16 @@ For ambiguous queries, request clarification before proceeding with a best-guess
         .describe("Library name to search for and retrieve a Context7-compatible library ID."),
     },
     async ({ libraryName }) => {
-      const searchResponse = await searchLibraries(libraryName);
+      const searchResponse: SearchResponse = await searchLibraries(libraryName);
 
-      if (!searchResponse || !searchResponse.results) {
+      if (!searchResponse.results || searchResponse.results.length === 0) {
         return {
           content: [
             {
               type: "text",
-              text: "Failed to retrieve library documentation data from Context7",
-            },
-          ],
-        };
-      }
-
-      if (searchResponse.results.length === 0) {
-        return {
-          content: [
-            {
-              type: "text",
-              text: "No documentation libraries available",
+              text: searchResponse.error
+                ? searchResponse.error
+                : "Failed to retrieve library documentation data from Context7",
             },
           ],
         };
@@ -143,12 +135,12 @@ ${resultsText}`,
         ),
     },
     async ({ context7CompatibleLibraryID, tokens = DEFAULT_MINIMUM_TOKENS, topic = "" }) => {
-      const documentationText = await fetchLibraryDocumentation(context7CompatibleLibraryID, {
+      const fetchDocsResponse = await fetchLibraryDocumentation(context7CompatibleLibraryID, {
         tokens,
         topic,
       });
 
-      if (!documentationText) {
+      if (!fetchDocsResponse) {
         return {
           content: [
             {
@@ -163,7 +155,7 @@ ${resultsText}`,
         content: [
           {
             type: "text",
-            text: documentationText,
+            text: fetchDocsResponse,
           },
         ],
       };

src/lib/api.ts

@@ -8,19 +8,30 @@ const DEFAULT_TYPE = "txt";
  * @param query The search query
  * @returns Search results or null if the request fails
  */
-export async function searchLibraries(query: string): Promise<SearchResponse | null> {
+export async function searchLibraries(query: string): Promise<SearchResponse> {
   try {
     const url = new URL(`${CONTEXT7_API_BASE_URL}/v1/search`);
     url.searchParams.set("query", query);
     const response = await fetch(url);
     if (!response.ok) {
-      console.error(`Failed to search libraries: ${response.status}`);
-      return null;
+      const errorCode = response.status;
+      if (errorCode === 429) {
+        console.error(`Rate limited due to too many requests. Please try again later.`);
+        return {
+          results: [],
+          error: `Rate limited due to too many requests. Please try again later.`,
+        } as SearchResponse;
+      }
+      console.error(`Failed to search libraries. Please try again later. Error code: ${errorCode}`);
+      return {
+        results: [],
+        error: `Failed to search libraries. Please try again later. Error code: ${errorCode}`,
+      } as SearchResponse;
     }
     return await response.json();
   } catch (error) {
     console.error("Error searching libraries:", error);
-    return null;
+    return { results: [], error: `Error searching libraries: ${error}` } as SearchResponse;
   }
 }
 
@@ -51,8 +62,15 @@ export async function fetchLibraryDocumentation(
       },
     });
     if (!response.ok) {
-      console.error(`Failed to fetch documentation: ${response.status}`);
-      return null;
+      const errorCode = response.status;
+      if (errorCode === 429) {
+        const errorMessage = `Rate limited due to too many requests. Please try again later.`;
+        console.error(errorMessage);
+        return errorMessage;
+      }
+      const errorMessage = `Failed to fetch documentation. Please try again later. Error code: ${errorCode}`;
+      console.error(errorMessage);
+      return errorMessage;
     }
     const text = await response.text();
     if (!text || text === "No content available" || text === "No context data available") {
@@ -60,7 +78,8 @@ export async function fetchLibraryDocumentation(
     }
     return text;
   } catch (error) {
-    console.error("Error fetching library documentation:", error);
-    return null;
+    const errorMessage = `Error fetching library documentation. Please try again later. ${error}`;
+    console.error(errorMessage);
+    return errorMessage;
   }
 }

src/lib/types.ts

@@ -14,6 +14,7 @@ export interface SearchResult {
 }
 
 export interface SearchResponse {
+  error?: string;
   results: SearchResult[];
 }