Introduce the inspector command

cmd/inspector.go

@@ -0,0 +1,84 @@
+package cmd
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"os/signal"
+	"strings"
+	"syscall"
+
+	"github.com/spf13/cobra"
+
+	internalcmd "github.com/mozilla-ai/mcpd/v2/internal/cmd"
+	cmdopts "github.com/mozilla-ai/mcpd/v2/internal/cmd/options"
+	"github.com/mozilla-ai/mcpd/v2/internal/runtime"
+)
+
+// InspectorCmd represents the 'inspector' command.
+type InspectorCmd struct {
+	*internalcmd.BaseCmd
+}
+
+// NewInspectorCmd creates a newly configured (Cobra) command.
+func NewInspectorCmd(baseCmd *internalcmd.BaseCmd, _ ...cmdopts.CmdOption) (*cobra.Command, error) {
+	c := &InspectorCmd{
+		BaseCmd: baseCmd,
+	}
+
+	cobraCommand := &cobra.Command{
+		Use:   "inspector [command] [args]",
+		Short: "Start the MCP inspector tool",
+		Long: "Start the MCP inspector tool via npx for quickly testing MCP servers. " +
+			"Optionally pass your desired command and arguments to the inspector. " +
+			"Note that the latest version of the inspector package is used (@modelcontextprotocol/inspector@latest). " +
+			"For more information, see https://modelcontextprotocol.io/docs/tools/inspector.",
+		RunE: c.run,
+	}
+
+	return cobraCommand, nil
+}
+
+// run is configured (via NewInspectorCmd) to be called by the Cobra framework when the command is executed.
+// It may return an error (or nil, when there is no error, or there was a graceful shutdown).
+func (c *InspectorCmd) run(cmd *cobra.Command, args []string) error {
+	ctx, stop := signal.NotifyContext(
+		context.Background(),
+		os.Interrupt,
+		syscall.SIGTERM, syscall.SIGINT,
+	)
+	defer stop()
+
+	// Create a new npx process with the user provided arguments
+	// Bind the process's stdout and stderr to our own for streaming output
+	npxArgs := append([]string{"@modelcontextprotocol/inspector@latest"}, args...)
+	npxCommand := exec.CommandContext(ctx, string(runtime.NPX), npxArgs...)
+	npxCommand.Stdout = os.Stdout
+	npxCommand.Stderr = os.Stderr
+
+	_, _ = fmt.Fprintf(
+		cmd.OutOrStdout(), "Starting the MCP inspector: npx %s...\n",
+		strings.Join(npxArgs, " "),
+	)
+	err := npxCommand.Start()
+	if err != nil {
+		return fmt.Errorf("error running the inspector: %w", err)
+	}
+
+	_, _ = fmt.Fprintf(cmd.OutOrStdout(), "Press Ctrl+C to stop.\n")
+	err = npxCommand.Wait()
+
+	if errors.Is(ctx.Err(), context.Canceled) {
+		// Graceful shutdown with Ctrl+C (or SIGTERM)
+		_, _ = fmt.Fprintf(cmd.OutOrStdout(), "\nShutting down the inspector...\n")
+		return nil
+	}
+
+	if err != nil {
+		return fmt.Errorf("failed to run the inspector: %w", err)
+	}
+
+	return nil
+}

cmd/root.go

@@ -70,6 +70,7 @@ func NewRootCmd(c *RootCmd) (*cobra.Command, error) {
 		NewRemoveCmd,
 		NewDaemonCmd,
 		config.NewConfigCmd,
+		NewInspectorCmd,
 	}
 
 	for _, fn := range fns {

docs/tutorial.md

@@ -37,6 +37,15 @@ You can also restrict access to allow only specific tools:
 mcpd add time --tool get_current_time
 ```
 
+!!! tip "Experiment with MCP servers"
+    You can quickly experiment with MCP servers before properly adding them to
+    the `mcpd` configuration, by running the inspector tool:
+    ```bash
+    mcpd inspector
+    ```
+    For more information, please refer to the [official documentation](https://modelcontextprotocol.io/docs/tools/inspector)
+    of the tool.
+
 ---
 
 ## 4. Set Startup Arguments