Expose tool prompt guidelines to extensions

closes #4879

packages/coding-agent/src/core/agent-session.ts

@@ -759,13 +759,14 @@ export class AgentSession {
 	}
 
 	/**
-	 * Get all configured tools with name, description, parameter schema, and source metadata.
+	 * Get all configured tools with name, description, parameter schema, prompt guidelines, and source metadata.
 	 */
 	getAllTools(): ToolInfo[] {
 		return Array.from(this._toolDefinitions.values()).map(({ definition, sourceInfo }) => ({
 			name: definition.name,
 			description: definition.description,
 			parameters: definition.parameters,
+			promptGuidelines: definition.promptGuidelines,
 			sourceInfo,
 		}));
 	}