Merge pull request #244 from drivecore/feature/243-mcp-tools

Implement MCP Tools Support

Author: bhouston

packages/agent/src/core/mcp/index.ts

@@ -15,6 +15,8 @@ export interface McpConfig {
   servers?: McpServerConfig[];
   /** Default resources to load automatically */
   defaultResources?: string[];
+  /** Default tools to make available */
+  defaultTools?: string[];
 }
 
 /**

packages/agent/src/tools/browser/filterPageContent.ts

@@ -2,6 +2,8 @@ import { Readability } from '@mozilla/readability';
 import { JSDOM } from 'jsdom';
 import { Page } from 'playwright';
 
+const OUTPUT_LIMIT = 11 * 1024; // 10KB limit
+
 /**
  * Returns the raw HTML content of the page without any processing
  */
@@ -93,13 +95,22 @@ export async function filterPageContent(
   page: Page,
   pageFilter: 'simple' | 'none' | 'readability',
 ): Promise<string> {
+  let result: string = '';
   switch (pageFilter) {
     case 'none':
-      return getNoneProcessedDOM(page);
+      result = await getNoneProcessedDOM(page);
+      break;
     case 'readability':
-      return getReadabilityProcessedDOM(page);
+      result = await getReadabilityProcessedDOM(page);
+      break;
     case 'simple':
     default:
-      return getSimpleProcessedDOM(page);
+      result = await getSimpleProcessedDOM(page);
+      break;
+  }
+
+  if (result.length > OUTPUT_LIMIT) {
+    return result.slice(0, OUTPUT_LIMIT) + '...(truncated)';
   }
+  return result;
 }

packages/agent/src/tools/mcp.ts

@@ -28,6 +28,25 @@ const getResourceSchema = z.object({
     .describe('URI of the resource to fetch in the format "scheme://path"'),
 });
 
+// Parameters for listTools method
+const listToolsSchema = z.object({
+  server: z
+    .string()
+    .optional()
+    .describe('Optional server name to filter tools by'),
+});
+
+// Parameters for executeTool method
+const executeToolSchema = z.object({
+  uri: z
+    .string()
+    .describe('URI of the tool to execute in the format "scheme://path"'),
+  params: z
+    .record(z.unknown())
+    .optional()
+    .describe('Parameters to pass to the tool'),
+});
+
 // Return type for listResources
 const listResourcesReturnSchema = z.array(
   z.object({
@@ -39,6 +58,20 @@ const listResourcesReturnSchema = z.array(
 // Return type for getResource
 const getResourceReturnSchema = z.string();
 
+// Return type for listTools
+const listToolsReturnSchema = z.array(
+  z.object({
+    uri: z.string(),
+    name: z.string(),
+    description: z.string().optional(),
+    parameters: z.record(z.unknown()).optional(),
+    returns: z.record(z.unknown()).optional(),
+  }),
+);
+
+// Return type for executeTool - can be any JSON value
+const executeToolReturnSchema = z.unknown();
+
 // Map to store MCP clients
 const mcpClients = new Map<string, any>();
 
@@ -87,7 +120,7 @@ export function createMcpTool(config: McpConfig): Tool {
   return {
     name: 'mcp',
     description:
-      'Interact with Model Context Protocol (MCP) servers to retrieve resources',
+      'Interact with Model Context Protocol (MCP) servers to retrieve resources and execute tools',
     parameters: z.discriminatedUnion('method', [
       z.object({
         method: z.literal('listResources'),
@@ -97,6 +130,14 @@ export function createMcpTool(config: McpConfig): Tool {
         method: z.literal('getResource'),
         params: getResourceSchema,
       }),
+      z.object({
+        method: z.literal('listTools'),
+        params: listToolsSchema.optional(),
+      }),
+      z.object({
+        method: z.literal('executeTool'),
+        params: executeToolSchema,
+      }),
     ]),
     parametersJsonSchema: zodToJsonSchema(
       z.discriminatedUnion('method', [
@@ -108,15 +149,33 @@ export function createMcpTool(config: McpConfig): Tool {
           method: z.literal('getResource'),
           params: getResourceSchema,
         }),
+        z.object({
+          method: z.literal('listTools'),
+          params: listToolsSchema.optional(),
+        }),
+        z.object({
+          method: z.literal('executeTool'),
+          params: executeToolSchema,
+        }),
       ]),
     ),
-    returns: z.union([listResourcesReturnSchema, getResourceReturnSchema]),
+    returns: z.union([
+      listResourcesReturnSchema,
+      getResourceReturnSchema,
+      listToolsReturnSchema,
+      executeToolReturnSchema,
+    ]),
     returnsJsonSchema: zodToJsonSchema(
-      z.union([listResourcesReturnSchema, getResourceReturnSchema]),
+      z.union([
+        listResourcesReturnSchema,
+        getResourceReturnSchema,
+        listToolsReturnSchema,
+        executeToolReturnSchema,
+      ]),
     ),
 
     execute: async ({ method, params }, { logger }) => {
-      // Extract the server name from a resource URI
+      // Extract the server name from a URI (resource or tool)
       function getServerNameFromUri(uri: string): string | undefined {
         const match = uri.match(/^([^:]+):\/\//);
         return match ? match[1] : undefined;
@@ -180,6 +239,64 @@ export function createMcpTool(config: McpConfig): Tool {
         logger.verbose(`Fetching resource: ${uri}`);
         const resource = await client.resource(uri);
         return resource.content;
+      } else if (method === 'listTools') {
+        // List available tools from MCP servers
+        const tools: any[] = [];
+        const serverFilter = params?.server;
+
+        // If a specific server is requested, only check that server
+        if (serverFilter) {
+          const client = mcpClients.get(serverFilter);
+          if (client) {
+            try {
+              logger.verbose(`Fetching tools from server: ${serverFilter}`);
+              const serverTools = await client.tools();
+              tools.push(...(serverTools as any[]));
+            } catch (error) {
+              logger.error(
+                `Failed to fetch tools from server ${serverFilter}:`,
+                error,
+              );
+            }
+          } else {
+            logger.warn(`Server not found: ${serverFilter}`);
+          }
+        } else {
+          // Otherwise, check all servers
+          for (const [serverName, client] of mcpClients.entries()) {
+            try {
+              logger.verbose(`Fetching tools from server: ${serverName}`);
+              const serverTools = await client.tools();
+              tools.push(...(serverTools as any[]));
+            } catch (error) {
+              logger.error(
+                `Failed to fetch tools from server ${serverName}:`,
+                error,
+              );
+            }
+          }
+        }
+
+        return tools;
+      } else if (method === 'executeTool') {
+        // Execute a tool from an MCP server
+        const { uri, params: toolParams = {} } = params;
+
+        // Parse the URI to determine which server to use
+        const serverName = getServerNameFromUri(uri);
+        if (!serverName) {
+          throw new Error(`Could not determine server from URI: ${uri}`);
+        }
+
+        const client = mcpClients.get(serverName);
+        if (!client) {
+          throw new Error(`Server not found: ${serverName}`);
+        }
+
+        // Use the MCP SDK to execute the tool
+        logger.verbose(`Executing tool: ${uri} with params:`, toolParams);
+        const result = await client.tool(uri, toolParams);
+        return result;
       }
 
       throw new Error(`Unknown method: ${method}`);
@@ -188,20 +305,36 @@ export function createMcpTool(config: McpConfig): Tool {
     logParameters: (params, { logger }) => {
       if (params.method === 'listResources') {
         logger.verbose(
-          `Listing MCP resources${params.params?.server ? ` from server: ${params.params.server}` : ''}`,
+          `Listing MCP resources${
+            params.params?.server ? ` from server: ${params.params.server}` : ''
+          }`,
         );
       } else if (params.method === 'getResource') {
         logger.verbose(`Fetching MCP resource: ${params.params.uri}`);
+      } else if (params.method === 'listTools') {
+        logger.verbose(
+          `Listing MCP tools${
+            params.params?.server ? ` from server: ${params.params.server}` : ''
+          }`,
+        );
+      } else if (params.method === 'executeTool') {
+        logger.verbose(`Executing MCP tool: ${params.params.uri}`);
       }
     },
 
     logReturns: (result, { logger }) => {
       if (Array.isArray(result)) {
-        logger.verbose(`Found ${result.length} MCP resources`);
-      } else {
+        if (result.length > 0 && 'description' in result[0]) {
+          logger.verbose(`Found ${result.length} MCP tools`);
+        } else {
+          logger.verbose(`Found ${result.length} MCP resources`);
+        }
+      } else if (typeof result === 'string') {
         logger.verbose(
           `Retrieved MCP resource content (${result.length} characters)`,
         );
+      } else {
+        logger.verbose(`Executed MCP tool and received result`);
       }
     },
   };

packages/cli/README.md

@@ -204,6 +204,9 @@ export default {
 
     // Optional: Default context resources to load
     defaultResources: ['company-docs://api/reference'],
+
+    // Optional: Default tools to make available
+    defaultTools: ['company-docs://tools/search'],
   },
 };
 ```
@@ -212,6 +215,25 @@ When MCP is configured, the agent will have access to a new `mcp` tool that allo
 
 - List available resources from configured MCP servers
 - Fetch resources to use as context for its work
+- List available tools from configured MCP servers
+- Execute tools provided by MCP servers
+
+#### Using MCP Tools
+
+MCP tools allow the agent to execute functions provided by external services through the Model Context Protocol. The agent can:
+
+1. Discover available tools using `mcp.listTools()`
+2. Execute a tool using `mcp.executeTool({ uri: 'server-name://path/to/tool', params: { ... } })`
+
+Tools can provide various capabilities like:
+
+- Searching documentation
+- Accessing databases
+- Interacting with APIs
+- Performing specialized calculations
+- Accessing proprietary services
+
+Each tool has a URI that identifies it, along with parameters it accepts and the type of result it returns.
 
 ### CLI-Only Options