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.deno.ts

@@ -164,6 +164,45 @@ export class DenoTool extends BaseToolWrapper {
     }
   }
 
+  public getToolExplanation(): string {
+    return `## Tool: deno
+Execute TypeScript/JavaScript code in a sandboxed Deno environment with fine-grained permission control.
+
+### Actions:
+
+**execute** - Execute TypeScript/JavaScript code and return stdout/stderr
+Parameters:
+  - code (required): TypeScript/JavaScript code to execute
+  - permissions (optional): Array of Deno permissions to grant. Options: "all", "env", "net", "read", "write", "run", "sys", "ffi", "hrtime". Default: none (fully sandboxed)
+
+Example - Simple execution:
+<tool_call>
+  <tool>deno</tool>
+  <action>execute</action>
+  <params>{"code": "console.log('Hello from Deno!');"}</params>
+</tool_call>
+
+Example - With network permission:
+<tool_call>
+  <tool>deno</tool>
+  <action>execute</action>
+  <params>{"code": "const resp = await fetch('https://api.example.com/data');\\nconsole.log(await resp.text());", "permissions": ["net"]}</params>
+</tool_call>
+
+**executeWithResult** - Execute code that outputs JSON on the last line of stdout
+Parameters:
+  - code (required): Code that console.logs a JSON value on the final line
+  - permissions (optional): Array of Deno permissions to grant
+
+Example:
+<tool_call>
+  <tool>deno</tool>
+  <action>executeWithResult</action>
+  <params>{"code": "const result = { sum: 1 + 2, product: 2 * 3 };\\nconsole.log(JSON.stringify(result));"}</params>
+</tool_call>
+`;
+  }
+
   public getCallSummary(action: string, params: Record<string, unknown>): string {
     const code = params.code as string;
     const permissions = (params.permissions as string[]) || [];