[BUG] MCP Client Tool Timeout Issue in Multi-Agent Orchestration

[Cerrix]

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

1.3.0

Python Version

3.13

Operating System

macOS 15.5

Installation Method

pip

Steps to Reproduce

Description

I'm experiencing an issue with the MCP client tool in a Strands multi-agent orchestrator implementation. When tools take longer than approximately 2 minutes to execute, the agent appears to freeze while waiting for the MCP response, and the final orchestrated response is never generated.

Steps to Reproduce

Create a multi-agent orchestrator using Strands agents as Tools (MCPs)
Set up multiple tools with varying execution times (some quick, some taking >2 minutes)
In my case, I'm calling 3 tools:

1. Current time (quick response)
2. online search (returns in ~31s)
3. online research (more complex) - (returns in ~3m28s)

Execute the orchestrator with these tools

Expected Behavior

The orchestrator should wait for all tools to complete and then generate the final response, regardless of how long individual tools take to execute.

Actual Behavior

• Tools that complete quickly (under 2 minutes) return successfully
• Tools that take longer than ~2 minutes to complete appear to execute successfully at the Lambda level
• However, the agent gets frozen waiting for the MCP response from these longer-running tools
• The orchestrator never generates the final response, even though all individual tools eventually complete their execution
• No explicit errors are thrown

Additional Context

• When using faster models, the issue doesn't occur
• The logs show successful tool execution, but the orchestration process seems to time out
• From the traces, it appears the long-running tools do eventually complete their execution, but their results aren't properly incorporated into the orchestration

Possible Solution

No response

Related Issues

No response

[kozodoi]

+1. I observe similar silent timeout behavior when running A Strands with streamablehttp_client MCP client with tools.