Python: Bug in multi-tool parameter parsing when using BedrockChatCompletion with the Converse Stream API #12202

Describe the bug
When an agent runs with BedrockChatCompletion using the Converse Stream API, tool parameters are not correctly parsed when more than 1 tool is used. For instance, if tool_a and tool_b are going to be executed with parameters {"param_11": "value_11"} and {"param_21": "value_21"} respectively, the parsing of content blocks in BedrockChatCompletion produces {"param_11": "value_11"}{"param_21": "value_21"} and {"param_21": "value_21"}, which is wrong (in addition to be invalid JSON for the first).

To Reproduce
Define a plugin with at least 2 tools (with at least 1 parameter each) and an agent with BedrockChatCompletion using the Converse Stream API. Then, ask the agent to run the 2 tools.

Expected behavior
Tool calls and their parameters should be correctly parsed.

Platform

• Language: Python
• Source: main branch of repository
• AI model: any