Add external_web_access to WebSearchTool for Responses API web_search

[ymuichiro]

Please read this first

• Have you read the docs? YES. I read the Agents SDK docs and the OpenAI web search docs, including the live internet access section.
• Have you searched for related issues? YES. I found related work such as PR feat: Add external_web_access option to WebSearchTool #2143 and issue/PR Web search tool updates #1592/Fix #1592 Web search tool updates #1601, but I could not find an open issue specifically tracking external_web_access support in WebSearchTool.

Describe the feature

Please add external_web_access: bool | None = None to WebSearchTool and pass it through to the Responses API web_search tool payload.

Background:

• In the OpenAI Responses API, web_search supports external_web_access: false to disable live internet access and use cached/indexed results only.
• In the current Agents SDK, WebSearchTool exposes user_location, filters, and search_context_size, but not external_web_access.
• As a result, SDK users cannot explicitly choose cache-only / offline-like behavior when using the built-in web search tool.

Example API:

from agents import Agent, WebSearchTool

agent = Agent(
    name="Research agent",
    model="gpt-5",
    tools=[
        WebSearchTool(
            search_context_size="medium",
            external_web_access=False,
        )
    ],
)

Expected request payload:

{
    "type": "web_search",
    "search_context_size": "medium",
    "external_web_access": False,
}

This would be useful for:

• Workflows that prefer reproducibility and want cached/indexed results only.
• Policy or compliance requirements that do not allow live web access.
• Keeping the Agents SDK aligned with the existing Responses API capability.

Related:

• PR feat: Add external_web_access option to WebSearchTool #2143: feat: Add external_web_access option to WebSearchTool (closed / unmerged)
• Issue Web search tool updates #1592 / PR Fix #1592 Web search tool updates #1601: other web search updates were added, but external_web_access support is still missing

[seratch]

I've confirmed the parameter now works.