feat: 支持duckduckgo搜索插件

app/api/langchain-tools/duckduckgo.ts

@@ -0,0 +1,32 @@
+import { SafeSearchType, search } from "duck-duck-scrape";
+import { convert as htmlToText } from "html-to-text";
+import { Tool } from "langchain/tools";
+
+export class DuckDuckGo extends Tool {
+  name = "duckduckgo_search";
+  maxResults = 4;
+
+  /** @ignore */
+  async _call(input: string) {
+    const searchResults = await search(input, {
+      safeSearch: SafeSearchType.OFF,
+    });
+
+    if (searchResults.noResults) {
+      return "No good search result found";
+    }
+
+    const results = searchResults.results
+      .slice(0, this.maxResults)
+      .map(
+        ({ title, description, url }) =>
+          `title:${title}\ncontent:${htmlToText(description)}\nurl:${url}`,
+      )
+      .join("\n\n");
+
+    return results;
+  }
+
+  description =
+    "a search engine. useful for when you need to answer questions about current events. input should be a search query.";
+}