feat(tools): add getToolExplanation() method with XML examples for LLM tool calling

Each tool now provides comprehensive documentation including parameter
schemas and concrete <tool_call> XML examples. This helps smaller LLMs
understand the exact format required for tool invocation.

ts/smartagent.tools.browser.ts

@@ -176,6 +176,59 @@ export class BrowserTool extends BaseToolWrapper {
     }
   }
 
+  public getToolExplanation(): string {
+    return `## Tool: browser
+Interact with web pages - take screenshots, generate PDFs, and execute JavaScript on pages.
+
+### Actions:
+
+**screenshot** - Take a screenshot of a webpage
+Parameters:
+  - url (required): URL of the page to screenshot
+
+Example:
+<tool_call>
+  <tool>browser</tool>
+  <action>screenshot</action>
+  <params>{"url": "https://example.com"}</params>
+</tool_call>
+
+**pdf** - Generate a PDF from a webpage
+Parameters:
+  - url (required): URL of the page to convert to PDF
+
+Example:
+<tool_call>
+  <tool>browser</tool>
+  <action>pdf</action>
+  <params>{"url": "https://example.com/report"}</params>
+</tool_call>
+
+**evaluate** - Execute JavaScript code on a webpage and return the result
+Parameters:
+  - url (required): URL of the page to run the script on
+  - script (required): JavaScript code to execute (must return a value)
+
+Example:
+<tool_call>
+  <tool>browser</tool>
+  <action>evaluate</action>
+  <params>{"url": "https://example.com", "script": "document.querySelectorAll('a').length"}</params>
+</tool_call>
+
+**getPageContent** - Get the text content and title of a webpage
+Parameters:
+  - url (required): URL of the page to get content from
+
+Example:
+<tool_call>
+  <tool>browser</tool>
+  <action>getPageContent</action>
+  <params>{"url": "https://example.com"}</params>
+</tool_call>
+`;
+  }
+
   public getCallSummary(action: string, params: Record<string, unknown>): string {
     switch (action) {
       case 'screenshot':