Custom tools via MCP (#153)

**Added a custom MCP server table and MCP view page**
This is a (UI)
tools run in both chat and can be monitored via a playbook
- Allows the user to view mcp servers(only .ts for now) added to the
local mcp-source file along with their file name, enable or disable an
mcp server, and access a dropdown to view server information and
available tools(and their descriptions) for the selected mcp server
- The mcp-view page is accessible via the view details button in the
dropdown
- The mcp-view page allows an mcp server to be deleted from the db and
the local files
- The mcp-view page allows an mcp tool to be run from the mcp-view page
if the server is enabled
- The mcp server table has an add mcp server button that brings the user
to a page with an upload/drag and drop mechanism to add an mcp server
directly to the mcp-source local file. When the server is added, it is
automatically built(using the build:mcp-servers script) to be run as a
.js file by the Agents local mcp client.
- currently mcp servers are run locally using the stdio protocol

**Added a tools page(UI)** 

- allows the user to view all the built in and enabled custom tools and
their details, as well as run them. This includes the mcp server name,
version, enabled/disabled/not run before(needs to be added to db)
status, and Available tools

**Local mcp-source file**
In the local mcp-source file, users can add custom mcp tools directly to
the file. This can also be done via the add mcp servers button
page(disabled for now)

- users can build a .js file from a .ts mcp server file using the
build:mcp-servers, this must be done before a server is available

**Test MCP servers**

- added simple servers with basic tools to test that the mcp server and
its tools are working, eg: (multiplication, add, modulo) tools using two
parameters, a testingTool that outputs the input.

---------

Signed-off-by: Alexis Rico <[email protected]>
Co-authored-by: Alexis Rico <[email protected]>

Author: PineappleChild

.gitignore

@@ -24,3 +24,5 @@ tsconfig.tsbuildinfo
 *.bun-build
 
 .eval-run-id
+
+dist

apps/dbagent/mcp-source/mcp-postgres.ts

@@ -0,0 +1,132 @@
+import { Server } from '@modelcontextprotocol/sdk/server/index.js';
+import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';
+import {
+  CallToolRequestSchema,
+  ListResourcesRequestSchema,
+  ListToolsRequestSchema,
+  ReadResourceRequestSchema
+} from '@modelcontextprotocol/sdk/types.js';
+import pg from 'pg';
+
+const server = new Server(
+  {
+    name: 'postgres',
+    version: '0.1.0'
+  },
+  {
+    capabilities: {
+      resources: {},
+      tools: {}
+    }
+  }
+);
+
+const databaseUrl = process.env.DATABASE_URL;
+if (!databaseUrl) {
+  throw new Error('DATABASE_URL environment variable is not set');
+}
+
+const resourceBaseUrl = new URL(databaseUrl);
+resourceBaseUrl.protocol = 'postgres:';
+resourceBaseUrl.password = '';
+
+const pool = new pg.Pool({
+  connectionString: databaseUrl
+});
+
+const SCHEMA_PATH = 'schema';
+
+server.setRequestHandler(ListResourcesRequestSchema, async () => {
+  const client = await pool.connect();
+  try {
+    const result = await client.query("SELECT table_name FROM information_schema.tables WHERE table_schema = 'public'");
+    return {
+      resources: result.rows.map((row) => ({
+        uri: new URL(`${row.table_name}/${SCHEMA_PATH}`, resourceBaseUrl).href,
+        mimeType: 'application/json',
+        name: `"${row.table_name}" database schema`
+      }))
+    };
+  } finally {
+    client.release();
+  }
+});
+
+server.setRequestHandler(ReadResourceRequestSchema, async (request) => {
+  const resourceUrl = new URL(request.params.uri);
+
+  const pathComponents = resourceUrl.pathname.split('/');
+  const schema = pathComponents.pop();
+  const tableName = pathComponents.pop();
+
+  if (schema !== SCHEMA_PATH) {
+    throw new Error('Invalid resource URI');
+  }
+
+  const client = await pool.connect();
+  try {
+    const result = await client.query(
+      'SELECT column_name, data_type FROM information_schema.columns WHERE table_name = $1',
+      [tableName]
+    );
+
+    return {
+      contents: [
+        {
+          uri: request.params.uri,
+          mimeType: 'application/json',
+          text: JSON.stringify(result.rows, null, 2)
+        }
+      ]
+    };
+  } finally {
+    client.release();
+  }
+});
+
+server.setRequestHandler(ListToolsRequestSchema, async () => {
+  return {
+    tools: [
+      {
+        name: 'query',
+        description: 'Run a read-only SQL query',
+        inputSchema: {
+          type: 'object',
+          properties: {
+            sql: { type: 'string' }
+          }
+        }
+      }
+    ]
+  };
+});
+
+server.setRequestHandler(CallToolRequestSchema, async (request) => {
+  if (request.params.name === 'query') {
+    const sql = request.params.arguments?.sql as string;
+
+    const client = await pool.connect();
+    try {
+      await client.query('BEGIN TRANSACTION READ ONLY');
+      const result = await client.query(sql);
+      return {
+        content: [{ type: 'text', text: JSON.stringify(result.rows, null, 2) }],
+        isError: false
+      };
+    } catch (error) {
+      throw error;
+    } finally {
+      client.query('ROLLBACK').catch((error) => console.warn('Could not roll back transaction:', error));
+
+      client.release();
+    }
+  }
+  throw new Error(`Unknown tool: ${request.params.name}`);
+});
+
+async function runServer() {
+  const transport = new StdioServerTransport();
+  await server.connect(transport);
+}
+
+runServer().catch(console.error);

apps/dbagent/mcp-source/tsconfig.json

@@ -0,0 +1,12 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "ES2022",
+    "moduleResolution": "node",
+    "esModuleInterop": true,
+    "strict": true,
+    "skipLibCheck": true,
+    "outDir": "./dist"
+  },
+  "include": ["./*.ts"]
+}

apps/dbagent/migrations/0008_mcp_servers.sql

@@ -0,0 +1,19 @@
+CREATE TABLE "mcp_servers" (
+	"id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+	"name" text NOT NULL,
+	"server_name" text NOT NULL,
+	"file_path" text NOT NULL,
+	"version" text NOT NULL,
+	"enabled" boolean DEFAULT true NOT NULL,
+	"env_vars" jsonb DEFAULT '{}' :: jsonb NOT NULL,
+	"created_at" timestamp DEFAULT now() NOT NULL,
+	CONSTRAINT "uq_mcp_servers_name" UNIQUE("name"),
+	CONSTRAINT "uq_mcp_servers_server_name" UNIQUE("server_name")
+);
+
+--> statement-breakpoint
+ALTER TABLE
+	"mcp_servers" ENABLE ROW LEVEL SECURITY;
+
+--> statement-breakpoint
+CREATE POLICY "mcp_servers_policy" ON "mcp_servers" AS PERMISSIVE FOR ALL TO "authenticated_user" USING (true);