MCP broken for remote `url` HTTP servers, like GitHub (but works for STDIO with `args`)

[vorburger]

https://docs.enola.dev/use/mcp/#list-mcp-tools ./enola -vvv mcp list-tools is broken:

2025-11-09 00:38:21 INFO dev.enola.ai.mcp.McpLoader opt Get (optional) search_brave
2025-11-09 00:38:21 INFO io.modelcontextprotocol.client.transport.StdioClientTransport lambda$connect$1 MCP server starting.
2025-11-09 00:38:21 INFO io.modelcontextprotocol.client.transport.StdioClientTransport lambda$connect$1 MCP server started
2025-11-09 00:38:21 WARNING dev.enola.ai.mcp.McpServerStdErrLogConsumer accept classpath:/enola.dev/ai/mcp.yaml#search_brave : Emulate Docker CLI using podman. Create /etc/containers/nodocker to quiet msg.
2025-11-09 00:38:22 INFO io.modelcontextprotocol.client.LifecycleInitializer lambda$doInitialize$4 Server response with Protocol: 2024-11-05, Capabilities: ServerCapabilities[completions=null, experimental=null, logging=LoggingCapabilities[], prompts=null, resources=null, tools=ToolCapabilities[listChanged=true]], Info: Implementation[name=brave-search-mcp-server, title=Brave Search MCP Server, version=2.0.10] and Instructions Use this server to search the Web for various types of data via the Brave Search API.
2025-11-09 00:38:22 INFO dev.enola.ai.mcp.McpLoader createSyncClient classpath:/enola.dev/ai/mcp.yaml#search_brave initializing: InitializeResult[protocolVersion=2024-11-05, capabilities=ServerCapabilities[completions=null, experimental=null, logging=LoggingCapabilities[], prompts=null, resources=null, tools=ToolCapabilities[listChanged=true]], serverInfo=Implementation[name=brave-search-mcp-server, title=Brave Search MCP Server, version=2.0.10], instructions=Use this server to search the Web for various types of data via the Brave Search API., meta=null]
2025-11-09 00:38:22 INFO dev.enola.ai.mcp.McpLoader createSyncClient classpath:/enola.dev/ai/mcp.yaml#search_brave fully initialized: brave-search-mcp-server @ 2.0.10

2025-11-09 00:38:22 INFO dev.enola.ai.mcp.McpLoader opt Get (optional) github
2025-11-09 00:38:22 WARNING io.modelcontextprotocol.client.LifecycleInitializer handleException Handling exception
java.lang.RuntimeException: Failed to send message: DummyEvent[responseInfo=jdk.internal.net.http.ResponseInfoImpl@76f25b1a]
        at io.modelcontextprotocol.client.transport.HttpClientStreamableHttpTransport.lambda$sendMessage$28(HttpClientStreamableHttpTransport.java:568)
        at reactor.core.publisher.FluxFlatMap$FlatMapMain.onNext(FluxFlatMap.java:388)
        at reactor.core.publisher.MonoFlatMapMany$FlatMapManyInner.onNext(MonoFlatMapMany.java:251)
        at reactor.core.publisher.FluxCreate$BufferAsyncSink.drain(FluxCreate.java:880)
        at reactor.core.publisher.FluxCreate$BufferAsyncSink.next(FluxCreate.java:805)
        at reactor.core.publisher.FluxCreate$SerializedFluxSink.next(FluxCreate.java:163)
        at io.modelcontextprotocol.client.transport.ResponseSubscribers$BodilessResponseLineSubscriber.hookOnComplete(ResponseSubscribers.java:315)
        at reactor.core.publisher.BaseSubscriber.onComplete(BaseSubscriber.java:197)
        at org.reactivestreams.FlowAdapters$FlowToReactiveSubscriber.onComplete(FlowAdapters.java:221)
        at java.net.http/jdk.internal.net.http.LineSubscriberAdapter$LineSubscription.loop(LineSubscriberAdapter.java:430)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$LockingRestartableTask.run(SequentialScheduler.java:182)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run(SequentialScheduler.java:149)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run(SequentialScheduler.java:207)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:280)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:233)
        at java.net.http/jdk.internal.net.http.LineSubscriberAdapter$LineSubscription.signalComplete(LineSubscriberAdapter.java:193)
        at java.net.http/jdk.internal.net.http.LineSubscriberAdapter.onComplete(LineSubscriberAdapter.java:114)
        at java.net.http/jdk.internal.net.http.common.HttpBodySubscriberWrapper.complete(HttpBodySubscriberWrapper.java:293)
        at java.net.http/jdk.internal.net.http.common.HttpBodySubscriberWrapper.onComplete(HttpBodySubscriberWrapper.java:401)
        at java.net.http/jdk.internal.net.http.ResponseContent$FixedLengthBodyParser.accept(ResponseContent.java:629)
        at java.net.http/jdk.internal.net.http.ResponseContent$FixedLengthBodyParser.accept(ResponseContent.java:540)
        at java.net.http/jdk.internal.net.http.Http1Response$BodyReader.handle(Http1Response.java:707)
        at java.net.http/jdk.internal.net.http.Http1Response$BodyReader.handle(Http1Response.java:635)
        at java.net.http/jdk.internal.net.http.Http1Response$Receiver.accept(Http1Response.java:527)
        at java.net.http/jdk.internal.net.http.Http1Response$BodyReader.tryAsyncReceive(Http1Response.java:665)
        at java.net.http/jdk.internal.net.http.Http1AsyncReceiver.flush(Http1AsyncReceiver.java:233)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$LockingRestartableTask.run(SequentialScheduler.java:182)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run(SequentialScheduler.java:149)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$TryEndDeferredCompleter.complete(SequentialScheduler.java:324)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run(SequentialScheduler.java:151)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run(SequentialScheduler.java:207)
        at java.net.http/jdk.internal.net.http.HttpClientImpl$DelegatingExecutor.execute(HttpClientImpl.java:177)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:282)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:251)
        at java.net.http/jdk.internal.net.http.Http1AsyncReceiver.asyncReceive(Http1AsyncReceiver.java:468)
        at java.net.http/jdk.internal.net.http.Http1AsyncReceiver$Http1TubeSubscriber.onNext(Http1AsyncReceiver.java:589)
        at java.net.http/jdk.internal.net.http.Http1AsyncReceiver$Http1TubeSubscriber.onNext(Http1AsyncReceiver.java:546)
        at java.net.http/jdk.internal.net.http.common.SSLTube$DelegateWrapper.onNext(SSLTube.java:210)
        at java.net.http/jdk.internal.net.http.common.SSLTube$SSLSubscriberWrapper.onNext(SSLTube.java:492)
        at java.net.http/jdk.internal.net.http.common.SSLTube$SSLSubscriberWrapper.onNext(SSLTube.java:295)
        at java.net.http/jdk.internal.net.http.common.SubscriberWrapper$DownstreamPusher.run1(SubscriberWrapper.java:316)
        at java.net.http/jdk.internal.net.http.common.SubscriberWrapper$DownstreamPusher.run(SubscriberWrapper.java:259)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$LockingRestartableTask.run(SequentialScheduler.java:182)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run(SequentialScheduler.java:149)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run(SequentialScheduler.java:207)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:280)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:233)
        at java.net.http/jdk.internal.net.http.common.SubscriberWrapper.outgoing(SubscriberWrapper.java:232)
        at java.net.http/jdk.internal.net.http.common.SubscriberWrapper.outgoing(SubscriberWrapper.java:198)
        at java.net.http/jdk.internal.net.http.common.SSLFlowDelegate$Reader.processData(SSLFlowDelegate.java:465)
        at java.net.http/jdk.internal.net.http.common.SSLFlowDelegate$Reader$ReaderDownstreamPusher.run(SSLFlowDelegate.java:283)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$LockingRestartableTask.run(SequentialScheduler.java:182)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run(SequentialScheduler.java:149)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run(SequentialScheduler.java:207)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
        at java.base/java.lang.Thread.run(Thread.java:1583)

java.lang.RuntimeException: Client failed to initialize by explicit API call
        at io.modelcontextprotocol.client.LifecycleInitializer.lambda$withInitialization$2(LifecycleInitializer.java:288)
        at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:94)
        at reactor.core.publisher.SerializedSubscriber.onError(SerializedSubscriber.java:124)
        at reactor.core.publisher.FluxTimeout$TimeoutMainSubscriber.onError(FluxTimeout.java:220)
        at reactor.core.publisher.FluxMap$MapSubscriber.onError(FluxMap.java:134)
        at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:106)
        at reactor.core.publisher.Operators.error(Operators.java:198)
        at reactor.core.publisher.MonoError.subscribe(MonoError.java:53)
        at reactor.core.publisher.Mono.subscribe(Mono.java:4576)
        at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:103)
        at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onError(FluxPeekFuseable.java:234)
        at reactor.core.publisher.MonoFlatMap$FlatMapMain.onError(MonoFlatMap.java:180)
        at reactor.core.publisher.MonoFlatMap$FlatMapMain.onError(MonoFlatMap.java:180)
        at reactor.core.publisher.FluxHandle$HandleSubscriber.onError(FluxHandle.java:213)
        at reactor.core.publisher.SerializedSubscriber.onError(SerializedSubscriber.java:124)
        at reactor.core.publisher.FluxTimeout$TimeoutMainSubscriber.onError(FluxTimeout.java:220)
        at reactor.core.publisher.MonoCreate$DefaultMonoSink.error(MonoCreate.java:205)
        at io.modelcontextprotocol.spec.McpClientSession.lambda$sendRequest$9(McpClientSession.java:268)
        at reactor.core.publisher.LambdaMonoSubscriber.doError(LambdaMonoSubscriber.java:155)
        at reactor.core.publisher.LambdaMonoSubscriber.onError(LambdaMonoSubscriber.java:150)
        at reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onError(FluxContextWrite.java:121)
        at reactor.core.publisher.MonoCreate$DefaultMonoSink.error(MonoCreate.java:205)
        at io.modelcontextprotocol.client.transport.HttpClientStreamableHttpTransport.lambda$sendMessage$31(HttpClientStreamableHttpTransport.java:577)
        at reactor.core.publisher.FluxOnErrorReturn$ReturnSubscriber.onError(FluxOnErrorReturn.java:175)
        at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:106)
        at reactor.core.publisher.Operators.error(Operators.java:198)
        at reactor.core.publisher.FluxError.subscribe(FluxError.java:43)
        at reactor.core.publisher.Flux.subscribe(Flux.java:8891)
        at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:103)
        at reactor.core.publisher.FluxFlatMap$FlatMapMain.checkTerminated(FluxFlatMap.java:846)
        at reactor.core.publisher.FluxFlatMap$FlatMapMain.drainLoop(FluxFlatMap.java:612)
        at reactor.core.publisher.FluxFlatMap$FlatMapMain.drain(FluxFlatMap.java:592)
        at reactor.core.publisher.FluxFlatMap$FlatMapMain.onError(FluxFlatMap.java:455)
        at reactor.core.publisher.FluxFlatMap$FlatMapMain.checkTerminated(FluxFlatMap.java:846)
        at reactor.core.publisher.FluxFlatMap$FlatMapMain.drainLoop(FluxFlatMap.java:612)
        at reactor.core.publisher.FluxFlatMap$FlatMapMain.drain(FluxFlatMap.java:592)
        at reactor.core.publisher.FluxFlatMap$FlatMapMain.onError(FluxFlatMap.java:455)
        at reactor.core.publisher.FluxFlatMap$FlatMapMain.onNext(FluxFlatMap.java:418)
        at reactor.core.publisher.MonoFlatMapMany$FlatMapManyInner.onNext(MonoFlatMapMany.java:251)
        at reactor.core.publisher.FluxCreate$BufferAsyncSink.drain(FluxCreate.java:880)
        at reactor.core.publisher.FluxCreate$BufferAsyncSink.next(FluxCreate.java:805)
        at reactor.core.publisher.FluxCreate$SerializedFluxSink.next(FluxCreate.java:163)
        at io.modelcontextprotocol.client.transport.ResponseSubscribers$BodilessResponseLineSubscriber.hookOnComplete(ResponseSubscribers.java:315)
        at reactor.core.publisher.BaseSubscriber.onComplete(BaseSubscriber.java:197)
        at org.reactivestreams.FlowAdapters$FlowToReactiveSubscriber.onComplete(FlowAdapters.java:221)
        at java.net.http/jdk.internal.net.http.LineSubscriberAdapter$LineSubscription.loop(LineSubscriberAdapter.java:430)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$LockingRestartableTask.run(SequentialScheduler.java:182)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run(SequentialScheduler.java:149)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run(SequentialScheduler.java:207)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:280)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:233)
        at java.net.http/jdk.internal.net.http.LineSubscriberAdapter$LineSubscription.signalComplete(LineSubscriberAdapter.java:193)
        at java.net.http/jdk.internal.net.http.LineSubscriberAdapter.onComplete(LineSubscriberAdapter.java:114)
        at java.net.http/jdk.internal.net.http.common.HttpBodySubscriberWrapper.complete(HttpBodySubscriberWrapper.java:293)
        at java.net.http/jdk.internal.net.http.common.HttpBodySubscriberWrapper.onComplete(HttpBodySubscriberWrapper.java:401)
        at java.net.http/jdk.internal.net.http.ResponseContent$FixedLengthBodyParser.accept(ResponseContent.java:629)
        at java.net.http/jdk.internal.net.http.ResponseContent$FixedLengthBodyParser.accept(ResponseContent.java:540)
        at java.net.http/jdk.internal.net.http.Http1Response$BodyReader.handle(Http1Response.java:707)
        at java.net.http/jdk.internal.net.http.Http1Response$BodyReader.handle(Http1Response.java:635)
        at java.net.http/jdk.internal.net.http.Http1Response$Receiver.accept(Http1Response.java:527)
        at java.net.http/jdk.internal.net.http.Http1Response$BodyReader.tryAsyncReceive(Http1Response.java:665)
        at java.net.http/jdk.internal.net.http.Http1AsyncReceiver.flush(Http1AsyncReceiver.java:233)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$LockingRestartableTask.run(SequentialScheduler.java:182)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run(SequentialScheduler.java:149)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$TryEndDeferredCompleter.complete(SequentialScheduler.java:324)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run(SequentialScheduler.java:151)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run(SequentialScheduler.java:207)
        at java.net.http/jdk.internal.net.http.HttpClientImpl$DelegatingExecutor.execute(HttpClientImpl.java:177)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:282)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:251)
        at java.net.http/jdk.internal.net.http.Http1AsyncReceiver.asyncReceive(Http1AsyncReceiver.java:468)
        at java.net.http/jdk.internal.net.http.Http1AsyncReceiver$Http1TubeSubscriber.onNext(Http1AsyncReceiver.java:589)
        at java.net.http/jdk.internal.net.http.Http1AsyncReceiver$Http1TubeSubscriber.onNext(Http1AsyncReceiver.java:546)
        at java.net.http/jdk.internal.net.http.common.SSLTube$DelegateWrapper.onNext(SSLTube.java:210)
        at java.net.http/jdk.internal.net.http.common.SSLTube$SSLSubscriberWrapper.onNext(SSLTube.java:492)
        at java.net.http/jdk.internal.net.http.common.SSLTube$SSLSubscriberWrapper.onNext(SSLTube.java:295)
        at java.net.http/jdk.internal.net.http.common.SubscriberWrapper$DownstreamPusher.run1(SubscriberWrapper.java:316)
        at java.net.http/jdk.internal.net.http.common.SubscriberWrapper$DownstreamPusher.run(SubscriberWrapper.java:259)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$LockingRestartableTask.run(SequentialScheduler.java:182)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run(SequentialScheduler.java:149)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run(SequentialScheduler.java:207)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:280)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:233)
        at java.net.http/jdk.internal.net.http.common.SubscriberWrapper.outgoing(SubscriberWrapper.java:232)
        at java.net.http/jdk.internal.net.http.common.SubscriberWrapper.outgoing(SubscriberWrapper.java:198)
        at java.net.http/jdk.internal.net.http.common.SSLFlowDelegate$Reader.processData(SSLFlowDelegate.java:465)
        at java.net.http/jdk.internal.net.http.common.SSLFlowDelegate$Reader$ReaderDownstreamPusher.run(SSLFlowDelegate.java:283)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$LockingRestartableTask.run(SequentialScheduler.java:182)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run(SequentialScheduler.java:149)
        at java.net.http/jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run(SequentialScheduler.java:207)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
        at java.base/java.lang.Thread.run(Thread.java:1583)
        Suppressed: java.lang.Exception: #block terminated with an error
                at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:104)
                at reactor.core.publisher.Mono.block(Mono.java:1779)
                at io.modelcontextprotocol.client.McpSyncClient.initialize(McpSyncClient.java:189)
                at dev.enola.ai.mcp.McpLoader.createSyncClient(McpLoader.java:200)
                at dev.enola.ai.mcp.McpLoader.lambda$opt$0(McpLoader.java:128)
                at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1708)
                at dev.enola.ai.mcp.McpLoader.opt(McpLoader.java:128)
                at dev.enola.ai.mcp.cli.ListToolsCommand.call(ListToolsCommand.java:71)
                at dev.enola.ai.mcp.cli.ListToolsCommand.call(ListToolsCommand.java:46)
                at picocli.CommandLine.executeUserObject(CommandLine.java:2031)
                at picocli.CommandLine.access$1500(CommandLine.java:148)
                at picocli.CommandLine$RunLast.executeUserObjectOfLastSubcommandWithSameParent(CommandLine.java:2469)
                at picocli.CommandLine$RunLast.handle(CommandLine.java:2461)
                at picocli.CommandLine$RunLast.handle(CommandLine.java:2423)
                at picocli.CommandLine$AbstractParseResultHandler.execute(CommandLine.java:2277)
                at picocli.CommandLine$RunLast.execute(CommandLine.java:2425)
                at dev.enola.cli.common.LoggingMixin.executionStrategy(LoggingMixin.java:77)
                at picocli.CommandLine.execute(CommandLine.java:2174)
                at dev.enola.cli.common.CLI.execute(CLI.java:93)
                at dev.enola.cli.EnolaApplication.main(EnolaApplication.java:64)
Caused by: java.lang.RuntimeException: Failed to send message: DummyEvent[responseInfo=jdk.internal.net.http.ResponseInfoImpl@76f25b1a]
        at io.modelcontextprotocol.client.transport.HttpClientStreamableHttpTransport.lambda$sendMessage$28(HttpClientStreamableHttpTransport.java:568)
        at reactor.core.publisher.FluxFlatMap$FlatMapMain.onNext(FluxFlatMap.java:388)
        ... 55 more

It only affects and is something specific to remote url HTTP MCL servers, like GitHub - it works for others.

[vorburger]

https://docs.enola.dev/concepts/mcp/#github ./enola ai --agents=test/agents/github.agent.yaml --prompt "How many stars do the top 3 repos that I own on GitHub repo have? (Use the GitHub context tool to find by GitHub user name.)" is actually broken as well (not just list-tools).

Maybe this is another impact of #1859, but not fixed by #1862.

Clearly needs better regression testing - first (and then a fix).

[vorburger]

Clearly needs better regression testing - first

==> #1908 will provide that.

and then a fix

modelcontextprotocol/java-sdk#501 looks related, but has no solution yet.

modelcontextprotocol/java-sdk#433 (comment) looks interesting, and worth a try.

[vorburger]

Next step: Create standalone (JBang?) reproducer, and report upstream.

Then either properly debug existing implementation, or... re- implement with OkHttp, or Google HTTP client?

Best tackled with AI! #dogfood

[vorburger]

BTW until this is fixed, https://github.com/github/github-mcp-server#local-github-mcp-server instead of https://github.com/github/github-mcp-server#remote-github-mcp-server would do the trick, e.g. for #1732.