Python: Remove bespoke Foundry toolbox helpers; standardize on MCP for toolbox consumption (#5671)

* Remove Foundry toolbox helpers; standardize on MCP for toolbox consumption

- Remove RawFoundryChatClient.get_toolbox() and its fetch_toolbox import
- Remove fetch_toolbox, select_toolbox_tools, get_toolbox_tool_name,
  get_toolbox_tool_type, FoundryHostedToolType, ToolboxToolSelectionInput
  from agent_framework_foundry._tools
- Remove ExperimentalFeature.TOOLBOXES from _feature_stage.py (no consumers)
- Drop toolbox re-exports from agent_framework_foundry/__init__.py and
  agent_framework.foundry namespace
- Update _sanitize_foundry_response_tool docstring to remove toolbox framing;
  sanitization logic itself is unchanged
- Update _agent.py docstring: 'toolbox-fetched MCP' → 'hosted MCP'
- Delete tests/test_toolbox.py (all tests covered removed helpers)
- Update test_foundry_chat_client.py: rename/redoc tests that mentioned
  toolbox but test sanitization that remains
- Delete foundry_chat_client_with_toolbox.py (bespoke toolbox API sample)
- Delete foundry_toolbox_context_provider.py (relied on select_toolbox_tools)
- Rename foundry_chat_client_with_toolbox_mcp.py →
  foundry_chat_client_with_toolbox.py (canonical MCP pattern)
- Rewrite 04_foundry_toolbox/main.py to use MCPStreamableHTTPTool
- Update provider/README, context_providers/README, 04_foundry_toolbox/README

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix(samples): update 06_files sample to consume toolbox via MCP (#5670)

Replace removed get_toolbox/select_toolbox_tools APIs with
MCPStreamableHTTPTool, using allowed_tools=["code_interpreter"] to
select only the code interpreter from the toolbox endpoint.

Update .env.example and README to use FOUNDRY_TOOLBOX_ENDPOINT
instead of TOOLBOX_NAME.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix(foundry): remove non-existent toolbox helper APIs from README (#5670)

Remove the 'fetch, optionally filter, and pass tools directly' pattern
from the FoundryChatClient toolbox documentation, as select_toolbox_tools
and get_toolbox were removed. Only the MCP endpoint pattern is documented.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix(foundry): remove residual toolbox docstring references and reproduction report

Remove REPRODUCTION_REPORT.md (workflow artifact that should not be committed),
and update two remaining docstring references that still said 'toolbox reads'
/'toolbox definition' after the toolbox helpers were removed.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Python: Remove bespoke Foundry toolbox helpers; standardize on MCP for toolbox consumption

Fixes #5670

* fix(#5670): resolve toolbox endpoint from TOOLBOX_NAME fallback; add namespace regression tests

- Add _resolve_toolbox_endpoint() helper in 04_foundry_toolbox/main.py and
  06_files/main.py that prefers FOUNDRY_TOOLBOX_ENDPOINT but falls back to
  deriving the MCP URL from FOUNDRY_PROJECT_ENDPOINT + TOOLBOX_NAME — fixing
  the startup KeyError when agents are deployed via azd provision (which injects
  TOOLBOX_NAME, not FOUNDRY_TOOLBOX_ENDPOINT).
- Update 04_foundry_toolbox/.env.example to use FOUNDRY_TOOLBOX_ENDPOINT
  (consistent with 06_files).
- Add TOOLBOX_NAME env var to 06_files/agent.yaml so deployed agents have it
  available for the fallback derivation.
- Update both READMEs to document the two ways to supply the toolbox endpoint.
- Add test_foundry_namespace_no_longer_exposes_toolbox_helpers() with negative
  assertions for FoundryHostedToolType, get_toolbox_tool_name,
  get_toolbox_tool_type, and select_toolbox_tools — guarding against accidental
  re-introduction of removed symbols.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix(samples): fail fast on empty FOUNDRY_TOOLBOX_ENDPOINT; add unit tests

Addresses review feedback for #5670:

- In _resolve_toolbox_endpoint() (04_foundry_toolbox/main.py and
  06_files/main.py) change the walrus-operator check from a truthy
  test to an explicit 'is not None' guard.  An explicitly set empty
  string now raises ValueError immediately with a clear message
  instead of silently falling through to the fallback URL
  construction.

- Add tests/samples/hosting/test_toolbox_endpoint.py covering both
  sample modules:
    (a) FOUNDRY_TOOLBOX_ENDPOINT set → returned as-is
    (b) FOUNDRY_TOOLBOX_ENDPOINT set to empty string → ValueError
    (c) fallback constructs URL from FOUNDRY_PROJECT_ENDPOINT + TOOLBOX_NAME,
        stripping trailing slashes
    (d) neither variable group set → KeyError

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Address review feedback: remove extraneous test and docstring content

- Remove test_foundry_namespace_no_longer_exposes_toolbox_helpers (no longer warranted)
- Remove docstring from _agent.py _prepare_tools_for_openai (extraneous)
- Trim _chat_client.py _prepare_tools_for_openai docstring to one-liner (toolbox references no longer relevant)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: remove remaining extraneous docstring from RawFoundryChatClient._prepare_tools_for_openai

Address review comment on PR #5671: reviewer noted the description
isn't warranted now that toolbox helpers have been removed. Matches
the pattern in RawFoundryAgentChatClient which has no docstring.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <copilot@github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

python/packages/foundry/README.md

@@ -21,32 +21,7 @@ For hosted `FoundryAgent`, the toolbox must already be attached to the agent in
 
 ### Using toolboxes with `FoundryChatClient`
 
-There are two patterns for wiring a toolbox into a `FoundryChatClient`-backed agent.
-
-**1. Fetch, optionally filter, and pass the tools directly**
-
-Load the toolbox from the Microsoft Foundry project, optionally select a subset of its tools, and hand them to an `Agent` alongside any other tools you own:
-
-```python
-from agent_framework import Agent
-from agent_framework.foundry import FoundryChatClient, select_toolbox_tools
-
-client = FoundryChatClient(...)
-toolbox = await client.get_toolbox("my-toolbox", version="3")
-
-# Pass the whole toolbox:
-agent = Agent(client=client, tools=toolbox)
-
-# Or filter to a subset first:
-selected = select_toolbox_tools(toolbox, include_types=["code_interpreter", "mcp"])
-agent = Agent(client=client, tools=selected)
-```
-
-See [`foundry_chat_client_with_toolbox.py`](../../samples/02-agents/providers/foundry/foundry_chat_client_with_toolbox.py) for a full example, including combining multiple toolboxes.
-
-**2. Connect to the toolbox's MCP endpoint with `MCPStreamableHTTPTool`**
-
-Each toolbox is reachable as an MCP server. Instead of fetching and fanning out its individual tool definitions, you can point a MAF `MCPStreamableHTTPTool` at the toolbox's MCP endpoint — the agent then discovers and calls its tools over MCP at runtime:
+Each toolbox is reachable as an MCP server. Connect to the toolbox's MCP endpoint with `MCPStreamableHTTPTool` — the agent then discovers and calls its tools over MCP at runtime:
 
 ```python
 from agent_framework import Agent, MCPStreamableHTTPTool