fix(coding-agent): add tool promptGuidelines support fixes #1720

packages/coding-agent/examples/extensions/README.md

@@ -33,7 +33,7 @@ cp permission-gate.ts ~/.pi/agent/extensions/
 | `question.ts` | Demonstrates `ctx.ui.select()` for asking the user questions with custom UI |
 | `questionnaire.ts` | Multi-question input with tab bar navigation between questions |
 | `tool-override.ts` | Override built-in tools (e.g., add logging/access control to `read`) |
-| `dynamic-tools.ts` | Register tools after startup (`session_start`) and at runtime via command |
+| `dynamic-tools.ts` | Register tools after startup (`session_start`) and at runtime via command, with prompt snippets and tool-specific prompt guidelines |
 | `built-in-tool-renderer.ts` | Custom compact rendering for built-in tools (read, bash, edit, write) while keeping original behavior |
 | `minimal-mode.ts` | Override built-in tool rendering for minimal display (only tool calls, no output in collapsed mode) |
 | `truncated-tool.ts` | Wraps ripgrep with proper output truncation (50KB/2000 lines) |

packages/coding-agent/examples/extensions/dynamic-tools.ts

@@ -35,6 +35,7 @@ export default function dynamicToolsExtension(pi: ExtensionAPI) {
 			label,
 			description: `Echo a message with prefix: ${prefix}`,
 			promptSnippet: `Echo back user-provided text with ${prefix.trim()} prefix`,
+			promptGuidelines: ["Use this tool when the user asks for exact echo output."],
 			parameters: ECHO_PARAMS,
 			async execute(_toolCallId, params) {
 				return {