First cut of the smithy-mcp CLI #677

adwsingh · 2025-04-30T02:59:40Z

Issue #, if available:

Description of changes:

Currently supports two commands,

configure -> This has further subcommands which allow adding bundles to the config.
start-server -> This starts an MCP server for a given pre-configured bundle.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

...s-codegen/src/main/java/software/amazon/smithy/java/codegen/types/JavaTypeCodegenPlugin.java

.../src/main/java/software/amazon/smithy/java/aws/mcp/cli/commands/AddAwsServiceToolBundle.java

...r/src/main/java/software/amazon/smithy/java/aws/servicebundle/bundler/AwsServiceBundler.java

rhernandez35 · 2025-05-05T04:46:52Z

...r/src/main/java/software/amazon/smithy/java/aws/servicebundle/bundler/AwsServiceBundler.java

    private static String loadModel(String path) {
        try (var reader = new BufferedReader(new InputStreamReader(
                Objects.requireNonNull(AwsServiceBundler.class.getResourceAsStream(path)),
                StandardCharsets.UTF_8))) {
-            return reader.lines().collect(Collectors.joining());
+            return reader.lines().collect(Collectors.joining("\n"));
        } catch (Exception e) {
            throw new RuntimeException(e);
        }


We should hoist this to Bundler as a protected final method. I've already messed this up twice and I'll keep messing it up every time I rewrite it.

mcp/mcp-cli-api/src/main/java/software/amazon/smithy/java/mcp/cli/ConfigUtils.java

rhernandez35 · 2025-05-05T04:56:12Z

mcp/mcp-cli-api/src/main/java/software/amazon/smithy/java/mcp/cli/SmithyMcpCommand.java

+            execute(config);
+            return 0;
+        } catch (IllegalArgumentException e) {
+            System.out.println("Invalid input : [" + e.getMessage() + "]");


Why println here and LOG in the Exception arm?

Please don't discard the stack trace. Do e.printStackTrace(System.out) if you must, although we should likely be using the logger here (unless you intended for this to go to the mcp client's logs, in which case stderr is a better choice)

So the idea was we only emit messages for errors and only print stack traces. I didn't want to log a stack trace for wrong inputs.

I think I need to do a second pass on logging, and also configure the logger. Will cleanup logging and println in the CLIs in a followup.

rhernandez35 · 2025-05-05T04:56:31Z

mcp/mcp-cli/src/main/java/software/amazon/smithy/java/mcp/cli/VersionProvider.java

+
+    @Override
+    public String[] getVersion() throws Exception {
+        return new String[] {IoUtils.readUtf8Resource(VersionProvider.class, "VERSION").trim()};


I tried adding a space but Spotless keeps changing it back to this.

mcp/mcp-cli/src/main/java/software/amazon/smithy/java/mcp/cli/commands/AddSmithyToolBundle.java

rhernandez35 · 2025-05-07T04:38:20Z

mcp/mcp-bundle-api/build.gradle.kts


-extra["displayName"] = "Smithy :: Java :: Model Bundler"
-extra["moduleName"] = "software.amazon.smithy.java.modelbundle.api"
+extra["displayName"] = "Smithy :: Java :: MCP Bundler"


Leave this in the current module. There's nothing intrinsically tied to MCP in this module, and I want to use the bundle format to drive smithy-call in the future.

rhernandez35 · 2025-05-07T04:41:00Z

...e/src/main/java/software/amazon/smithy/java/aws/servicebundle/provider/AwsServiceBundle.java

+            var endpoint = URI.create(Objects.requireNonNull(serviceMetadata.getEndpoints().get(input.getAwsRegion()),
+                    "no endpoint for region " + input.getAwsRegion()));
+
+            try (var sdkCredentialsProvider = ProfileCredentialsProvider.create(input.getAwsProfileName())) {


sdkCredentialsProvider will be closed when we return from this method but the reference will live in identityResolver. I don't think we want the try-with-resources here.

rhernandez35 · 2025-05-07T04:41:57Z

mcp/mcp-bundle-api/src/main/java/software/amazon/smithy/mcp/bundle/api/Bundler.java

+
+    public abstract Bundle bundle();
+
+    protected String loadModel(String path) {


This can be static or final

rhernandez35 · 2025-05-07T04:51:47Z

mcp/mcp-bundle-api/src/main/java/software/amazon/smithy/mcp/bundle/api/Bundles.java

+        var modelAssemble = new ModelAssembler().putProperty(ModelAssembler.ALLOW_UNKNOWN_TRAITS, true)
+                .addUnparsedModel("bundle.json", bundle.getModel());
+        var additionalInput = bundle.getAdditionalInput();
+        if (additionalInput != null) {


We're only running the streaming operation redaction logic when there's additional inputs, but we should always be doing it

rhernandez35 · 2025-05-07T04:52:38Z

mcp/mcp-bundle-api/src/main/java/software/amazon/smithy/mcp/bundle/api/Bundles.java

+                            skipOperation = true;
+                            break;


Did checkstyle complain about using a labeled break or is this a personal style choice?

rhernandez35 · 2025-05-07T04:57:20Z

mcp/mcp-cli-api/src/main/java/software/amazon/smithy/java/mcp/cli/ConfigUtils.java

+
+        if (!CONFIG_PATH.toFile().exists()) {
+            // Create an empty JSON object as the default config
+            Files.write(CONFIG_PATH, toJson(DEFAULT_CONFIG_PROVIDER.getConfig()), StandardOpenOption.CREATE_NEW);


This will throw if the file was created in between us check if it existed and us trying to create it

rhernandez35 · 2025-05-07T04:58:11Z

mcp/mcp-cli-api/src/main/java/software/amazon/smithy/java/mcp/cli/ConfigUtils.java

+     * @throws IOException If there's an error writing to the file
+     */
+    public static void updateConfig(Config config) throws IOException {
+        Files.write(CONFIG_PATH, toJson(config), StandardOpenOption.CREATE_NEW);


CREATE_NEW causes this to throw if the file already exists, so this will (almost?) always fail

rhernandez35 · 2025-05-07T04:59:12Z

...cp-cli-api/src/main/java/software/amazon/smithy/java/mcp/cli/EmptyDefaultConfigProvider.java

+
+import software.amazon.smithy.java.mcp.cli.model.Config;
+
+public class EmptyDefaultConfigProvider implements DefaultConfigProvider {


rhernandez35 · 2025-05-07T05:02:33Z

...e/src/main/java/software/amazon/smithy/java/aws/servicebundle/provider/AwsServiceBundle.java

-                .putSupportedAuthSchemes(StaticAuthSchemeResolver.staticScheme(authScheme));
+    public <C extends Client, B extends Client.Builder<C, B>> B configureClient(B clientBuilder) {
+        clientBuilder.addInterceptor(new AwsServiceClientInterceptor(serviceMetadata, authScheme));
+        clientBuilder.endpointResolver(EndpointResolver.staticEndpoint("http://dummyurl.com"));


use localhost. let's avoid using anything that could result in traffic being sent to a domain squatter.

adwsingh requested review from mtdowling and rhernandez35 April 30, 2025 03:12

adwsingh force-pushed the adwsingh/mcp-cli branch 4 times, most recently from ebda0cc to 5dd3763 Compare April 30, 2025 22:11

rhernandez35 reviewed May 5, 2025

View reviewed changes

adwsingh added 4 commits May 6, 2025 17:48

First cut of the smithy-mcp-cli

218662e

wip

781ef79

Everything working

ee81217

Adding Registry and list and add CLIs

7e272ef

adwsingh force-pushed the adwsingh/mcp-cli branch from 5dd3763 to 7e272ef Compare May 7, 2025 00:49

adwsingh added 7 commits May 6, 2025 17:50

Remove unused class

8e89952

Remove duplicate modules

ad29702

Remove model bundler modules

f5e7f5a

Use Files.write

9b165d8

Remove commented out code

8a7413c

More fixes

098b2f0

Directly return bundle location

73e2d02

adwsingh requested a review from rhernandez35 May 7, 2025 01:25

rhernandez35 reviewed May 7, 2025

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First cut of the smithy-mcp CLI #677

First cut of the smithy-mcp CLI #677

adwsingh commented Apr 30, 2025

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adwsingh May 7, 2025

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rhernandez35 May 7, 2025


		public abstract Bundle bundle();

		protected String loadModel(String path) {


		import software.amazon.smithy.java.mcp.cli.model.Config;

		public class EmptyDefaultConfigProvider implements DefaultConfigProvider {

First cut of the smithy-mcp CLI #677

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First cut of the smithy-mcp CLI #677

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adwsingh commented Apr 30, 2025

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