Feat/cli http

README.md

@@ -252,9 +252,12 @@ npx @modelcontextprotocol/inspector --cli node build/index.js --method resources
 # List available prompts
 npx @modelcontextprotocol/inspector --cli node build/index.js --method prompts/list
 
-# Connect to a remote MCP server
+# Connect to a remote MCP server (default is SSE transport)
 npx @modelcontextprotocol/inspector --cli https://my-mcp-server.example.com
 
+# Connect to a remote MCP server (with Streamable HTTP transport)
+npx @modelcontextprotocol/inspector --cli https://my-mcp-server.example.com --transport http
+
 # Call a tool on a remote server
 npx @modelcontextprotocol/inspector --cli https://my-mcp-server.example.com --method tools/call --tool-name remotetool --tool-arg param=value
 

cli/scripts/cli-tests.js

@@ -44,7 +44,10 @@ console.log(`${colors.BLUE}- Resource-related options (--uri)${colors.NC}`);
 console.log(
   `${colors.BLUE}- Prompt-related options (--prompt-name, --prompt-args)${colors.NC}`,
 );
-console.log(`${colors.BLUE}- Logging options (--log-level)${colors.NC}\n`);
+console.log(`${colors.BLUE}- Logging options (--log-level)${colors.NC}`);
+console.log(`${colors.BLUE}- Transport types (--transport http/sse/stdio)${colors.NC}`);
+console.log(`${colors.BLUE}- Transport inference from URL suffixes (/mcp, /sse)${colors.NC}`);
+console.log(`\n`);
 
 // Get directory paths
 const SCRIPTS_DIR = __dirname;
@@ -62,9 +65,11 @@ if (!fs.existsSync(OUTPUT_DIR)) {
 }
 
 // Create a temporary directory for test files
-const TEMP_DIR = fs.mkdirSync(path.join(os.tmpdir(), "mcp-inspector-tests"), {
-  recursive: true,
-});
+const TEMP_DIR = path.join(os.tmpdir(), "mcp-inspector-tests");
+fs.mkdirSync(TEMP_DIR, { recursive: true });
+
+// Track servers for cleanup
+let runningServers = [];
 
 process.on("exit", () => {
   try {
@@ -74,6 +79,23 @@ process.on("exit", () => {
       `${colors.RED}Failed to remove temp directory: ${err.message}${colors.NC}`,
     );
   }
+
+  runningServers.forEach(server => {
+    try {
+      process.kill(-server.pid);
+    } catch (e) {
+    }
+  });
+});
+
+process.on("SIGINT", () => {
+  runningServers.forEach(server => {
+    try {
+      process.kill(-server.pid);
+    } catch (e) {
+    }
+  });
+  process.exit(1);
 });
 
 // Use the existing sample config file
@@ -121,6 +143,11 @@ async function runBasicTest(testName, ...args) {
         stdio: ["ignore", "pipe", "pipe"],
       });
 
+      const timeout = setTimeout(() => {
+        console.log(`${colors.YELLOW}Test timed out: ${testName}${colors.NC}`);
+        child.kill();
+      }, 10000);
+
       // Pipe stdout and stderr to the output file
       child.stdout.pipe(outputStream);
       child.stderr.pipe(outputStream);
@@ -135,6 +162,7 @@ async function runBasicTest(testName, ...args) {
       });
 
       child.on("close", (code) => {
+        clearTimeout(timeout);
         outputStream.end();
 
         if (code === 0) {
@@ -201,6 +229,11 @@ async function runErrorTest(testName, ...args) {
         stdio: ["ignore", "pipe", "pipe"],
       });
 
+      const timeout = setTimeout(() => {
+        console.log(`${colors.YELLOW}Error test timed out: ${testName}${colors.NC}`);
+        child.kill();
+      }, 10000);
+
       // Pipe stdout and stderr to the output file
       child.stdout.pipe(outputStream);
       child.stderr.pipe(outputStream);
@@ -215,6 +248,7 @@ async function runErrorTest(testName, ...args) {
       });
 
       child.on("close", (code) => {
+        clearTimeout(timeout);
         outputStream.end();
 
         // For error tests, we expect a non-zero exit code
@@ -611,6 +645,69 @@ async function runTests() {
     "debug",
   );
 
+  console.log(
+    `\n${colors.YELLOW}=== Running HTTP Transport Tests ===${colors.NC}`,
+  );
+
+  console.log(`${colors.BLUE}Starting server-everything in streamableHttp mode.${colors.NC}`);
+  const httpServer = spawn("npx", ["@modelcontextprotocol/server-everything", "streamableHttp"], {
+    detached: true,
+    stdio: "ignore"
+  });
+  runningServers.push(httpServer);
+
+  await new Promise(resolve => setTimeout(resolve, 3000));
+
+  // Test 25: HTTP transport inferred from URL ending with /mcp
+  await runBasicTest(
+    "http_transport_inferred",
+    "http://127.0.0.1:3001/mcp",
+    "--cli",
+    "--method",
+    "tools/list",
+  );
+
+  // Test 26: HTTP transport with explicit --transport http flag
+  await runBasicTest(
+    "http_transport_with_explicit_flag",
+    "http://127.0.0.1:3001",
+    "--transport",
+    "http",
+    "--cli",
+    "--method",
+    "tools/list",
+  );
+
+  // Test 27: HTTP transport with suffix and --transport http flag
+  await runBasicTest(
+    "http_transport_with_explicit_flag_and_suffix",
+    "http://127.0.0.1:3001/mcp",
+    "--transport",
+    "http",
+    "--cli",
+    "--method",
+    "tools/list",
+  );
+
+  // Test 28: SSE transport given to HTTP server (should fail)
+  await runErrorTest(
+    "sse_transport_given_to_http_server",
+    "http://127.0.0.1:3001",
+    "--transport",
+    "sse",
+    "--cli",
+    "--method",
+    "tools/list",
+  );
+
+  // Kill HTTP server
+  try {
+    process.kill(-httpServer.pid);
+    console.log(`${colors.BLUE}HTTP server killed, waiting for port to be released...${colors.NC}`);
+  } catch (e) {
+    console.log(`${colors.RED}Error killing HTTP server: ${e.message}${colors.NC}`);
+  }
+
   // Print test summary
   console.log(`\n${colors.YELLOW}=== Test Summary ===${colors.NC}`);
   console.log(`${colors.GREEN}Passed: ${PASSED_TESTS}${colors.NC}`);

cli/src/index.ts

@@ -29,9 +29,13 @@ type Args = {
   logLevel?: LogLevel;
   toolName?: string;
   toolArg?: Record<string, string>;
+  transport?: "sse" | "stdio" | "http";
 };
 
-function createTransportOptions(target: string[]): TransportOptions {
+function createTransportOptions(
+  target: string[],
+  transport?: "sse" | "stdio" | "http",
+): TransportOptions {
   if (target.length === 0) {
     throw new Error(
       "Target is required. Specify a URL or a command to execute.",
@@ -50,16 +54,38 @@ function createTransportOptions(target: string[]): TransportOptions {
     throw new Error("Arguments cannot be passed to a URL-based MCP server.");
   }
 
+  let transportType: "sse" | "stdio" | "http";
+  if (transport) {
+    if (!isUrl && transport !== "stdio") {
+      throw new Error("Only stdio transport can be used with local commands.");
+    }
+    if (isUrl && transport === "stdio") {
+      throw new Error("stdio transport cannot be used with URLs.");
+    }
+    transportType = transport;
+  } else if (isUrl) {
+    const url = new URL(command);
+    if (url.pathname.endsWith("/mcp")) {
+      transportType = "http";
+    } else if (url.pathname.endsWith("/sse")) {
+      transportType = "sse";
+    } else {
+      transportType = "sse";
+    }
+  } else {
+    transportType = "stdio";
+  }
+
   return {
-    transportType: isUrl ? "sse" : "stdio",
+    transportType,
     command: isUrl ? undefined : command,
     args: isUrl ? undefined : commandArgs,
     url: isUrl ? command : undefined,
   };
 }
 
 async function callMethod(args: Args): Promise<void> {
-  const transportOptions = createTransportOptions(args.target);
+  const transportOptions = createTransportOptions(args.target, args.transport);
   const transport = createTransport(transportOptions);
   const client = new Client({
     name: "inspector-cli",
@@ -214,6 +240,22 @@ function parseArgs(): Args {
 
         return value as LogLevel;
       },
+    )
+    //
+    // Transport options
+    //
+    .option(
+      "--transport <type>",
+      "Transport type (sse, http, or stdio). Auto-detected from URL: /mcp → http, /sse → sse, commands → stdio",
+      (value: string) => {
+        const validTransports = ["sse", "http", "stdio"];
+        if (!validTransports.includes(value)) {
+          throw new Error(
+            `Invalid transport type: ${value}. Valid types are: ${validTransports.join(", ")}`,
+          );
+        }
+        return value as "sse" | "http" | "stdio";
+      },
     );
 
   // Parse only the arguments before --

cli/src/transport.ts

@@ -3,23 +3,35 @@ import {
   getDefaultEnvironment,
   StdioClientTransport,
 } from "@modelcontextprotocol/sdk/client/stdio.js";
+import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js";
 import type { Transport } from "@modelcontextprotocol/sdk/shared/transport.js";
 import { findActualExecutable } from "spawn-rx";
 
 export type TransportOptions = {
-  transportType: "sse" | "stdio";
+  transportType: "sse" | "stdio" | "http";
   command?: string;
   args?: string[];
   url?: string;
 };
 
 function createSSETransport(options: TransportOptions): Transport {
   const baseUrl = new URL(options.url ?? "");
-  const sseUrl = new URL("/sse", baseUrl);
+  const sseUrl = baseUrl.pathname.endsWith("/sse")
+    ? baseUrl
+    : new URL("/sse", baseUrl);
 
   return new SSEClientTransport(sseUrl);
 }
 
+function createHTTPTransport(options: TransportOptions): Transport {
+  const baseUrl = new URL(options.url ?? "");
+  const mcpUrl = baseUrl.pathname.endsWith("/mcp")
+    ? baseUrl
+    : new URL("/mcp", baseUrl);
+
+  return new StreamableHTTPClientTransport(mcpUrl);
+}
+
 function createStdioTransport(options: TransportOptions): Transport {
   let args: string[] = [];
 
@@ -67,6 +79,10 @@ export function createTransport(options: TransportOptions): Transport {
       return createSSETransport(options);
     }
 
+    if (transportType === "http") {
+      return createHTTPTransport(options);
+    }
+
     throw new Error(`Unsupported transport type: ${transportType}`);
   } catch (error) {
     throw new Error(