Introduce the inspector command
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Introduce the 'inspector' command, which starts the MCP inspector tool via an npx process for interaction with 'try me out' style MCP servers. Also, add a note to the docs.
peteski22
requested changes
Sep 3, 2025
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Thanks @michalismeng for picking this up, looks good! I added some suggestions, it would be great if you could take a look please.
Just re-tag me afterwards and we can get this approved and merged. 🥳
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| // NewInspectorCmd creates a newly configured (Cobra) command. | ||
| func NewInspectorCmd(baseCmd *internalcmd.BaseCmd, opt ...cmdopts.CmdOption) (*cobra.Command, error) { |
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Suggested change
| func NewInspectorCmd(baseCmd *internalcmd.BaseCmd, opt ...cmdopts.CmdOption) (*cobra.Command, error) { | |
| func NewInspectorCmd(baseCmd *internalcmd.BaseCmd, _ ...cmdopts.CmdOption) (*cobra.Command, error) { |
| package cmd | ||
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| import ( | ||
| "context" |
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| "context" | |
| "context" | |
| "errors" |
Required for errors.Is.
| BaseCmd: baseCmd, | ||
| } | ||
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| cobraCommand := &cobra.Command{ |
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❓ I think perhaps we should mention in the docs (long) which version of @modelcontextprotocol/inspector we run... or pin it explicitly to latest.
| npxCommand.Stdout = os.Stdout | ||
| npxCommand.Stderr = os.Stderr | ||
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| fmt.Printf("Starting the MCP inspector: npx %s...\n", strings.Join(npxArgs, " ")) |
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Please could you replace calls to fmt.Printf with fmt.Fprintf that use cmd.OutOrStdOut?
Suggested change
| fmt.Printf("Starting the MCP inspector: npx %s...\n", strings.Join(npxArgs, " ")) | |
| _, _ = fmt.Fprintf( | |
| cmd.OutOrStdout(), "Starting the MCP inspector: npx %s...\n", | |
| strings.Join(npxArgs, " "), | |
| ) |
| } | ||
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| if err != nil { | ||
| return fmt.Errorf("failed to run the inspector: %w", err) |
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| return fmt.Errorf("failed to run the inspector: %w", err) | |
| return fmt.Errorf("error running the inspector: %w", err) |
| @@ -37,6 +37,15 @@ You can also restrict access to allow only specific tools: | |||
| mcpd add time --tool get_current_time | |||
| ``` | |||
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| !!! note "Experiment with MCP servers" | |||
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| !!! note "Experiment with MCP servers" | |
| !!! tip "Experiment with MCP servers" |
| // 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"}, args...) | ||
| npxCommand := exec.CommandContext(ctx, "npx", npxArgs...) |
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| npxCommand := exec.CommandContext(ctx, "npx", npxArgs...) | |
| npxCommand := exec.CommandContext(ctx, string(runtime.NPX), npxArgs...) |
Note: requires "github.com/mozilla-ai/mcpd/v2/internal/runtime" to be imported.
| "github.com/spf13/cobra" | ||
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| internalcmd "github.com/mozilla-ai/mcpd/v2/internal/cmd" | ||
| cmdopts "github.com/mozilla-ai/mcpd/v2/internal/cmd/options" |
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| cmdopts "github.com/mozilla-ai/mcpd/v2/internal/cmd/options" | |
| cmdopts "github.com/mozilla-ai/mcpd/v2/internal/cmd/options" | |
| "github.com/mozilla-ai/mcpd/v2/internal/runtime" |
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What's changed
Introduce the 'inspector' command, which starts the MCP inspector tool. Internally it launches the inspector with
npx @modelcontextprotocol/inspectorand passes any addition arguments the user gives.Closes #51
(See the issue for some more details)
Notes
The issue mentions the following in the desired solution:
Currently,
mcpd inspectorprints to the terminal whatever the underlyingnpxprocess prints, so there will be dev-style details of the error:and in the UI we get a message from the inspector itself, for example:
Not sure if this is enough, glad to discuss if more is needed here.