[Flaky Test] RestChatAgentWithMcpConnectorIT.testChatAgentWithMcpStreamableHttpConnector

[nathaliellenaa]

What is the bug?
Flaky integration test, sample failing CI: https://github.com/opensearch-project/ml-commons/actions/runs/30130755579/job/89604709649

RestChatAgentWithMcpConnectorIT > testChatAgentWithMcpStreamableHttpConnector STANDARD_ERROR
    REPRODUCE WITH: ./gradlew ':opensearch-ml-plugin:integTest' --tests 'org.opensearch.ml.rest.RestChatAgentWithMcpConnectorIT.testChatAgentWithMcpStreamableHttpConnector' -Dtests.seed=B1F17290950072A -Dtests.security.manager=false -Dtests.locale=sq -Dtests.timezone=Asia/Harbin -Druntime.java=25 -Djava.security.properties=/__w/ml-commons/ml-commons/distribution/src/config/fips_java.security

RestChatAgentWithMcpConnectorIT > testChatAgentWithMcpStreamableHttpConnector FAILED
    org.opensearch.client.ResponseException: method [POST], host [http://127.0.0.1:39049/], URI [/_plugins/_ml/agents/EcpJlp8BShJKgHXiW35h/_execute], status line [HTTP/1.1 400 Bad Request]
    {"status":400,"error":{"type":"OpenSearchStatusException","reason":"Invalid Request","details":"Error from remote service: {\"message\":\"The provided request is not valid\"}"}}
        at __randomizedtesting.SeedInfo.seed([B1F17290950072A:FED5EB9E818EC05E]:0)
        at app//org.opensearch.client.RestClient.convertResponse(RestClient.java:498)
        at app//org.opensearch.client.RestClient.performRequest(RestClient.java:387)

        at app//org.opensearch.client.RestClient.performRequest(RestClient.java:362)

        at app//org.opensearch.ml.utils.TestHelper.performRequestWithRemoteRetry(TestHelper.java:216)
Suite: Test class org.opensearch.ml.rest.RestChatAgentWithMcpConnectorIT
        at app//org.opensearch.ml.utils.TestHelper.makeRequest(TestHelper.java:207)
  2> korr 25, 2026 6:40:39 E PARADITES org.opensearch.client.RestClient logResponse
  2> WARNING: request [DELETE http://[::1]:37057/.plugins-ml-mcp-tools] returned 1 warnings: [299 OpenSearch-3.8.0-SNAPSHOT-1a9c84fc5c7a40515ba89dd16bc1c3a772dc28af "this request accesses system indices: [.plugins-ml-mcp-tools], but in a future major version, direct access to system indices will be prevented by default"]
  2> REPRODUCE WITH: ./gradlew ':opensearch-ml-plugin:integTest' --tests 'org.opensearch.ml.rest.RestChatAgentWithMcpConnectorIT.testChatAgentWithMcpStreamableHttpConnector' -Dtests.seed=B1F17290950072A -Dtests.security.manager=false -Dtests.locale=sq -Dtests.timezone=Asia/Harbin -Druntime.java=25 -Djava.security.properties=/__w/ml-commons/ml-commons/distribution/src/config/fips_java.security
  2> org.opensearch.client.ResponseException: method [POST], host [http://127.0.0.1:39049/], URI [/_plugins/_ml/agents/EcpJlp8BShJKgHXiW35h/_execute], status line [HTTP/1.1 400 Bad Request]
        at app//org.opensearch.ml.utils.TestHelper.makeRequest(TestHelper.java:180)
        at app//org.opensearch.ml.rest.RestChatAgentWithMcpConnectorIT.testChatAgentWithMcpStreamableHttpConnector(RestChatAgentWithMcpConnectorIT.java:201)

RestChatAgentWithMcpConnectorIT STANDARD_ERROR
    NOTE: leaving temporary files on disk at: /__w/ml-commons/ml-commons/plugin/build/testrun/integTest/temp/org.opensearch.ml.rest.RestChatAgentWithMcpConnectorIT_B1F17290950072A-001
    NOTE: test params are: codec=Asserting(Lucene104): {}, docValues:{}, maxPointsInLeafNode=2043, maxMBSortInHeap=5.972259641969541, sim=Asserting(RandomSimilarity(queryNorm=false): {}), locale=sq, timezone=Asia/Harbin
    NOTE: Linux 6.17.0-1020-azure amd64/Azul Systems, Inc. 25.0.4 (64-bit)/cpus=4,threads=1,free=463889480,total=536870912
    NOTE: All tests run in this JVM: [HFAnalyzerIT, MLModelAutoReDeployerIT, MLContextManagementOverrideRestIT, MLContextManagementRestIT, RestBedRockInferenceIT, RestChatAgentIT, RestChatAgentWithMcpConnectorIT]
  1> [2026-07-24T22:40:15,653][INFO ][o.o.m.r.RestChatAgentWithMcpConnectorIT] [testChatAgentWithMcpStreamableHttpConnector] before test
  1> [2026-07-24T22:40:15,653][INFO ][o.o.m.r.RestChatAgentWithMcpConnectorIT] [testChatAgentWithMcpStreamableHttpConnector] initializing REST clients against [http://[::1]:34815, http://127.0.0.1:39049,/ http://[::1]:33129, http://127.0.0.1:35193,/ http://[::1]:37057, http://127.0.0.1:36245]/
  1> [2026-07-24T22:40:39,288][INFO ][o.o.m.r.RestChatAgentWithMcpConnectorIT] [testChatAgentWithMcpStreamableHttpConnector] after test
    {"status":400,"error":{"type":"OpenSearchStatusException","reason":"Invalid Request","details":"Error from remote service: {\"message\":\"The provided request is not valid\"}"}}
        at __randomizedtesting.SeedInfo.seed([B1F17290950072A:FED5EB9E818EC05E]:0)
        at app//org.opensearch.client.RestClient.convertResponse(RestClient.java:498)
        at app//org.opensearch.client.RestClient.performRequest(RestClient.java:387)
        at app//org.opensearch.client.RestClient.performRequest(RestClient.java:362)
        at app//org.opensearch.ml.utils.TestHelper.performRequestWithRemoteRetry(TestHelper.java:216)
        at app//org.opensearch.ml.utils.TestHelper.makeRequest(TestHelper.java:207)
        at app//org.opensearch.ml.utils.TestHelper.makeRequest(TestHelper.java:180)
        at app//org.opensearch.ml.rest.RestChatAgentWithMcpConnectorIT.testChatAgentWithMcpStreamableHttpConnector(RestChatAgentWithMcpConnectorIT.java:201)
  2> NOTE: leaving temporary files on disk at: /__w/ml-commons/ml-commons/plugin/build/testrun/integTest/temp/org.opensearch.ml.rest.RestChatAgentWithMcpConnectorIT_B1F17290950072A-001
  2> NOTE: test params are: codec=Asserting(Lucene104): {}, docValues:{}, maxPointsInLeafNode=2043, maxMBSortInHeap=5.972259641969541, sim=Asserting(RandomSimilarity(queryNorm=false): {}), locale=sq, timezone=Asia/Harbin
  2> NOTE: Linux 6.17.0-1020-azure amd64/Azul Systems, Inc. 25.0.4 (64-bit)/cpus=4,threads=1,free=463889480,total=536870912
  2> NOTE: All tests run in this JVM: [HFAnalyzerIT, MLModelAutoReDeployerIT, MLContextManagementOverrideRestIT, MLContextManagementRestIT, RestBedRockInferenceIT, RestChatAgentIT, RestChatAgentWithMcpConnectorIT]

How can one reproduce the bug?

REPRODUCE WITH: ./gradlew ':opensearch-ml-plugin:integTest' --tests 'org.opensearch.ml.rest.RestChatAgentWithMcpConnectorIT.testChatAgentWithMcpStreamableHttpConnector' -Dtests.seed=B1F17290950072A -Dtests.security.manager=false -Dtests.locale=sq -Dtests.timezone=Asia/Harbin -Druntime.java=25 -Djava.security.properties=/__w/ml-commons/ml-commons/distribution/src/config/fips_java.security

What is the expected behavior?
Test should consistently passing

What is your host/environment?

• OS: [e.g. iOS]
• Version [e.g. 22]
• Plugins

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Do you have any additional context?
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