Python: [Bug]: Foundry agent rejects tools with HTTP 400 on the preview path (allow_preview=True)

[vaibhav-patel]

Describe the bug

RawFoundryAgentChatClient (the client behind FoundryAgent) returns HTTP 400 invalid_payload — "Not allowed when agent is specified." (param: tools) — when a caller passes tools while the preview path is active (allow_preview=True).

RawFoundryAgentChatClient always targets a pre-provisioned Foundry agent (agent_name is required), and the service rejects requests that carry both an agent reference and tool declarations.

PR #5101 added stripping of tools / tool_choice / parallel_tool_calls in RawFoundryAgentChatClient._prepare_options(), but gated it behind if not self.allow_preview:. The preview path also specifies an agent — the identity is bound on the OpenAI client via project_client.get_openai_client(agent_name=...) — so tool declarations are still sent (and rejected) on that path.

Where

python/packages/foundry/agent_framework_foundry/_agent.py — RawFoundryAgentChatClient._prepare_options().

Expected behavior

Since this client always targets a pre-provisioned agent, tool declarations should be stripped from the request body on both the preview and non-preview paths. Tools are still invoked client-side by the function-invocation layer; their schemas must be defined on the Foundry agent in the service.

Related

• Partially fixed by Python: Strip tools from FoundryAgent request when agent_reference is present #5101 (non-preview path only).
• Fix: Python: Strip tools from Foundry agent request on the preview path (allow_preview=True) #6644.

[github-actions]

🤖 Automated triage reproduction notes (agent-authored — trust but verify)

Agent analysis

Repro: RawFoundryAgentChatClient._prepare_options() in python/packages/foundry/agent_framework_foundry/_agent.py (line 381) fails to strip tools/tool_choice/parallel_tool_calls when self.allow_preview is True because the stripping block is guarded by if not self.allow_preview:. Minimal repro: construct RawFoundryAgentChatClient with allow_preview=True, call _prepare_options with options containing tools — the result dict still contains tools/tool_choice/parallel_tool_calls, triggering HTTP 400 from the Foundry service. Fix: unconditionally strip these fields (remove the if not self.allow_preview: guard on lines 381-384).

• Failing test: python/packages/foundry/tests/foundry/test_issue_657_preview_tools_stripped.py
• Files examined: python/packages/foundry/agent_framework_foundry/_agent.py, python/packages/foundry/tests/foundry/test_foundry_agent.py, python/packages/foundry/pyproject.toml
• Tests run: python/packages/foundry/tests/foundry/test_issue_657_preview_tools_stripped.py
• Current version: 1.8.2