[Naveen Chatlapalli (1aifanatic)]

Motivation & Context

Since the MCP 2.x migration (#9236), step 3 of the "build your own claw" harness sample cannot connect to a Foundry Toolbox. _connect_foundry_toolbox() unpacks three values from streamable_http_client, but mcp 2.x yields (read, write), so it fails with ValueError: not enough values to unpack (expected 3, got 2) whenever FOUNDRY_TOOLBOX_ENDPOINT is set. Details in #9594.

Description & Review Guide

• What are the major changes?
  • read, write = await stack.enter_async_context(streamable_http_client(...)).
  • import httpx2 as httpx, and the PEP 723 dependency httpx becomes httpx2. mcp 2.x types http_client as httpx2.AsyncClient, and the declarative invoke_foundry_toolbox_mcp sample already uses this import. httpx2 keeps the Auth / AsyncClient / Timeout API, so _ToolboxAuth is unchanged.
• What is the impact of these changes? Sample only. Step 3 can open its Foundry Toolbox MCP session again.
• What do you want reviewers to focus on? Nothing special.

Verified by running the sample's own _connect_foundry_toolbox() against a local mcp 2.3.0 MCPServer over streamable HTTP, with the bearer-token provider stubbed:

	result
main	ValueError: not enough values to unpack (expected 3, got 2)
this PR	session initializes; list_tools() returns the server's tool

Pyright on the file goes from 2 errors to 0. ruff check and ruff format --check pass.

Related Issue

Fixes #9594

AI Assistance

• No material AI assistance was used.
• This is an AI-assisted contribution. I reviewed, understood, and verified all submitted content and accept responsibility for it.

AI assistance details: Claude Code helped find the breakage, implement the fix, build the local MCP server verification, and draft this description and the linked issue.

Contribution Checklist

• The code builds clean without any errors or warnings
• All unit tests pass, and I have added new tests where possible
• The PR follows the Contribution Guidelines
• This PR links to an agreed issue with no competing open PR, or the Related Issue section documents a trivial-change or repository-automation exception.
• This is not a breaking change. If it is a breaking change, add the breaking change label (or add "[BREAKING]" to the title prefix, before or after any language prefix) — a workflow keeps the label and title prefix in sync automatically.

🤖 Generated with Claude Code

[Copilot]

🟢 Approval recommended

The narrow sample-only changes address the reported compatibility failure consistently, with no blocking issues identified.

No open issues 🎉

What changed in this PR

Fixes the step 3 “build your own claw” sample’s Foundry Toolbox connection after the MCP 2.x migration, addressing #9594.

Changes:

• Updates the inline dependency and HTTP client import to httpx2.
• Unpacks the two transport streams returned by MCP 2.x, leaving authentication and session lifecycle unchanged.

File	Description
python/​samples/​02-agents/​harness/​build_your_own_claw/​claw_step03_scaling_capabilities.py	Aligns the HTTP client and transport unpacking with MCP 2.x.

_{Review effort: Balanced}