[BUG] Bedrock Marketplace model error

[yhou-uk]

Checks

• I have updated to the lastest minor and patch version of Strands
• I have checked the documentation and this is not expected behavior
• I have searched ./issues and there are no duplicates of my issue

Strands Version

0.1.6

Python Version

3.12.10

Operating System

macOS 15.5

Installation Method

pip

Steps to Reproduce

First Install Mistral-Small-24B-Instruct-2501 model from Bedrock Marketplace.
Provide model endpoint ARN in blow code example
code example:

import asyncio
from mcp import stdio_client, StdioServerParameters
from strands import Agent
from strands.tools.mcp import MCPClient
from strands.models import BedrockModel

async def main():
    # Connect to multiple MCP servers
    google_mcp_client = MCPClient(lambda: stdio_client(
        StdioServerParameters(
                command="npx",
                args=["-y", "@modelcontextprotocol/server-google-maps"],
                env={"GOOGLE_MAPS_API_KEY": "<GOOGLE_API>"})
            )
        )
    time_mcp_client = MCPClient(lambda: stdio_client(
        StdioServerParameters(
                command="npx",
                args=["-y", "time-mcp"])
            )
        )
    
    # Set up the clients using context managers (not async)
    with google_mcp_client, time_mcp_client:
        # Get tools from both clients
        tools = google_mcp_client.list_tools_sync() + time_mcp_client.list_tools_sync()
        
        # Define the model ID directly

        model_id = "<BEDROCK_MARKETPLACE_ENDPOINT_ARN>"

        bedrock_model = BedrockModel(
            model_id=model_id,
            streaming=False
        )
        
        # Create an agent with the model ID and tools
        print(f"Creating agent with model {model_id}...")
        
        agent = Agent(model=bedrock_model, tools=tools)
        response = agent("What are the top 3 Department stores in London?")
        print(f"Response: {response}")

        response = agent("Are they open now?")
        print(f"Follow-up response: {response}")

if __name__ == "__main__":
    asyncio.run(main())

Expected Behavior

It should complete the conversation and use correct tools to answer questions.

Actual Behavior

It shows below error:

strands.types.exceptions.EventLoopException: An error occurred (ValidationException) when calling the Converse operation: This model doesn't support the status field. Remove status and try again.

Additional Context

No response

Possible Solution

No response

Related Issues

No response

[awsarron]

Thanks for reporting this @yhou-uk, the team is taking a look in to it.

[Unshure]

Hi @yhou-uk, I dug into this issue a bit more, and it looks like the validation logic used by the models deployed via the Bedrock marketplace is a bit different from the validation logic used by Bedrock Foundation models. Specifically, the ToolResultBlock status field is ignored by non-claude foundation models, but causes a validation error in Bedrock marketplace models.

I am planning on doing some more testing to see if there are any other parameters like this that cause validation exceptions, and adding a new parameter to the BedrockModel provider to filter out these problematic parameters. Additionally, i'm planning on detecting this specific error message, and throwing a strands-specific message to encourage a user to enable this filtering parameter if the error is encountered.