docs: surface Kijiji AND-matching behavior in tool, API, and MCP responses

Kijiji zero-result queries (e.g. 'macbook air m1 apple silicon') are
confusing because the failure mode is non-obvious. Surface the root
cause everywhere the caller can see it:
- MCP tool description warns about AND-matching and gives a concrete
  before/after example
- API 404 body includes the actionable hint via emptySearchResponse(hint)
- Core scraper logs the built URL and tip on page-1 zero results
- MCP handler unwraps the API message field so the hint reaches the LLM

packages/api-server/src/routes/helpers.ts

@@ -31,9 +31,9 @@ export function parseNonNegativeIntegerParam(
   return value;
 }
 
-export function emptySearchResponse(): Response {
-  return Response.json(
-    { message: "Search didn't return any results!" },
-    { status: 404 },
-  );
+export function emptySearchResponse(hint?: string): Response {
+  const message = hint
+    ? `Search didn't return any results! ${hint}`
+    : "Search didn't return any results!";
+  return Response.json({ message }, { status: 404 });
 }

packages/api-server/src/routes/kijiji.ts

@@ -73,7 +73,10 @@ export async function kijijiRoute(req: Request): Promise<Response> {
         { hideUnstableResults: true },
       );
       if (items.results.length === 0 && items.unstableResults.length === 0) {
-        return emptySearchResponse();
+        return emptySearchResponse(
+          `Kijiji matches ALL words in the query against listing titles. ` +
+            `Try a shorter or more common query (e.g. "macbook air m1" instead of "macbook air m1 apple silicon").`,
+        );
       }
       return Response.json(items, { status: 200 });
     }
@@ -86,7 +89,10 @@ export async function kijijiRoute(req: Request): Promise<Response> {
       {},
     );
     if (!items || items.length === 0) {
-      return emptySearchResponse();
+      return emptySearchResponse(
+        `Kijiji matches ALL words in the query against listing titles. ` +
+          `Try a shorter or more common query (e.g. "macbook air m1" instead of "macbook air m1 apple silicon").`,
+      );
     }
     return Response.json(items, { status: 200 });
   } catch (error) {

packages/api-server/test/routes.test.ts

@@ -394,7 +394,8 @@ describe("API routes", () => {
 
     expect(response.status).toBe(404);
     const body = await response.json();
-    expect(body.message).toBe("Search didn't return any results!");
+    expect(body.message).toStartWith("Search didn't return any results!");
+    expect(body.message).toContain("Kijiji matches ALL words");
   });
 
   test("ebayRoute forwards maxItems to core in default mode", async () => {

packages/core/src/scrapers/kijiji.ts

@@ -893,7 +893,17 @@ export default async function fetchKijijiItems(
 
     const searchResults = parseSearch(searchHtml, BASE_URL);
     if (searchResults.length === 0) {
-      logger.log(`No more results found on page ${page}. Stopping pagination.`);
+      if (page === 1) {
+        logger.log(
+          `No results found on page 1. The search URL was: ${searchUrl}\n` +
+            `Tip: Kijiji matches ALL words in the query against listing titles. ` +
+            `Try a shorter or more common query (e.g. "macbook air m1" instead of "macbook air m1 apple silicon").`,
+        );
+      } else {
+        logger.log(
+          `No more results found on page ${page}. Stopping pagination.`,
+        );
+      }
       break;
     }
 

packages/mcp-server/src/protocol/handler.ts

@@ -138,7 +138,14 @@ export async function handleMcpRequest(req: Request): Promise<Response> {
             logger.error(
               `[MCP] Kijiji API error ${response.status}: ${errorText}`,
             );
-            throw new Error(`API returned ${response.status}: ${errorText}`);
+            let errorMessage = `API returned ${response.status}: ${errorText}`;
+            try {
+              const errorJson = JSON.parse(errorText) as { message?: string };
+              if (errorJson.message) errorMessage = errorJson.message;
+            } catch {
+              // not JSON — use raw text
+            }
+            throw new Error(errorMessage);
           }
           result = await response.json();
           logger.log(

packages/mcp-server/src/protocol/tools.ts

@@ -11,7 +11,11 @@ export const tools = [
       properties: {
         query: {
           type: "string",
-          description: "Search query for Kijiji listings",
+          description:
+            "Search query for Kijiji listings. " +
+            "Kijiji requires ALL words to appear in the listing title — keep queries short and use terms sellers actually write. " +
+            "Avoid marketing/brand phrases sellers don't use (e.g. use 'macbook air m1' not 'macbook air m1 apple silicon'). " +
+            "If the search returns no results, try a shorter or more common query.",
         },
         location: {
           type: "string",