Fix #138: Feature: Built-in billing/monetization for MCP tools via Ag...

src/tools/BaseTool.ts

@@ -115,6 +115,11 @@ export interface ToolExecution {
   taskSupport?: 'forbidden' | 'optional' | 'required';
 }
 
+export interface ToolPricing {
+  perCall?: number;
+  freeTier?: number;
+}
+
 export interface ContentAnnotations {
   audience?: ('user' | 'assistant')[];
   priority?: number;
@@ -177,6 +182,7 @@ export interface ToolProtocol extends SDKTool {
     icons?: MCPIcon[];
     annotations?: ToolAnnotations;
     execution?: ToolExecution;
+    pricing?: ToolPricing;
     outputSchema?: Record<string, unknown>;
     _meta?: Record<string, unknown>;
   };
@@ -227,6 +233,7 @@ export abstract class MCPTool<TInput extends Record<string, any> = any, TSchema
   icons?: MCPIcon[];
   annotations?: ToolAnnotations;
   execution?: ToolExecution;
+  pricing?: ToolPricing;
   protected outputSchemaShape?: z.ZodObject<any>;
   [key: string]: unknown;
 
@@ -861,6 +868,7 @@ export abstract class MCPTool<TInput extends Record<string, any> = any, TSchema
       ...(this.icons && this.icons.length > 0 && { icons: this.icons }),
       ...(this.annotations && Object.keys(this.annotations).length > 0 && { annotations: this.annotations }),
       ...(this.execution && Object.keys(this.execution).length > 0 && { execution: this.execution }),
+      ...(this.pricing && Object.keys(this.pricing).length > 0 && { pricing: this.pricing }),
       ...(this.outputSchemaShape && { outputSchema: this.generateOutputSchema() }),
       ...(this.app && {
         _meta: {

tests/tools/tool-metadata.test.ts

@@ -42,6 +42,22 @@ class ToolWithEmptyIcons extends MCPTool {
   async execute() { return 'ok'; }
 }
 
+class ToolWithPricing extends MCPTool {
+  name = 'priced_tool';
+  description = 'A tool with pricing';
+  pricing = { perCall: 0.001, freeTier: 100 };
+  schema = schema;
+  async execute() { return 'ok'; }
+}
+
+class ToolWithPartialPricing extends MCPTool {
+  name = 'partial_priced_tool';
+  description = 'A tool with partial pricing';
+  pricing = { perCall: 0.005 };
+  schema = schema;
+  async execute() { return 'ok'; }
+}
+
 describe('Tool Metadata', () => {
   describe('title', () => {
     it('should include title in toolDefinition when set', () => {
@@ -72,4 +88,21 @@ describe('Tool Metadata', () => {
       expect('icons' in tool.toolDefinition).toBe(false);
     });
   });
+
+  describe('pricing', () => {
+    it('should include pricing in toolDefinition when set', () => {
+      const tool = new ToolWithPricing();
+      expect(tool.toolDefinition.pricing).toEqual({ perCall: 0.001, freeTier: 100 });
+    });
+
+    it('should include partial pricing in toolDefinition', () => {
+      const tool = new ToolWithPartialPricing();
+      expect(tool.toolDefinition.pricing).toEqual({ perCall: 0.005 });
+    });
+
+    it('should not include pricing key when not set', () => {
+      const tool = new BasicTool();
+      expect('pricing' in tool.toolDefinition).toBe(false);
+    });
+  });
 });