Bedrock ConverseStream: toolResult DocumentType rejects valid JSON

[rbrtj]

Checkboxes for prior research

• I've gone through Developer Guide and API reference
• I've checked AWS Forums and StackOverflow.
• I've searched for previous similar issues and didn't find any solution.

Describe the bug

When using the Bedrock ConverseStream API, sending a toolResult field with a value that is a valid JSON type results in the error:

Bad Request - The format of the value at messages.3.content.0.toolResult.content.0.json is invalid. Provide a json object for the field and try again.

According to the API documentation and Smithy DocumentType spec, the toolResult field should accept any JSON-serializable value, not just objects.

Model used: claude-3-7-sonnet-20250219-v1

Regression Issue

• Select this option if this issue appears to be a regression.

SDK version number

@aws-sdk/client-bedrock-runtime": "^3.744.0"

Which JavaScript Runtime is this issue in?

Node.js

Details of the browser/Node.js/ReactNative version

v22.17.1

Reproduction Steps

1. Use HTTP client (I'm using axios) to make a direct HTTP request to the Bedrock ConverseStream API endpoint.
2. In the request payload, set the toolResult.content field to an array containing a json property with a non-object JSON value.

{
  messages: [
    {
      role: "user",
      content: [
        {
          toolResult: {
            toolUseId: "some-id",
            content: [
              { json: [] } // or { json: "foo" }, { json: 123 }, { json: true }, { json: null }
            ]
          }
        }
      ]
    }
  ]
}

3. Send the request to the Bedrock ConverseStream endpoint
4. Observe that the API responds with the error Provide a json object for the field and try again.
5. If you use an object for json (e.g., {json: { foo: "bar" } }) the request succeeds

Observed Behavior

When toolResult.content contains a json value that is not an object, the Bedrock ConverseStream API responds with an error message.

 Bad Request - The format of the value at messages.2.content.0.toolResult.content.0.json is invalid. Provide a json object for the field and try again.`

Expected Behavior

Either the API is updated to accept all valid JSON values or the types are updated to clarify that only objects are accepted.

Possible Solution

No response

Additional Information/Context

No response

[aBurmeseDev]

Hi @rbrtj - thanks for reporting. I'm reaching out to service team to get their insight and will keep it updated here. (ref P305367660)

[aBurmeseDev]

According to service team member:

The tool result content block should be a valid json object. Please see this https://docs.aws.amazon.com/bedrock/latest/APIReference/API_runtime_ToolResultContentBlock.html. Please see this example https://docs.aws.amazon.com/bedrock/latest/userguide/tool-use-examples.html on how to structure it

[github-actions]

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