feat: Make OpenAPI tool async

Merge https://github.com/google/adk-python/pull/2872

Closes https://github.com/google/adk-python/issues/787

The OpenAPI tool has been ported to the httpx client to make requests truly asynchronous.

COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/2872 from condorcet:async_openapi_tool bf83f73af93f624126462fb0bd41fef27c53a0b6
PiperOrigin-RevId: 864250822

src/google/adk/tools/openapi_tool/auth/auth_helpers.py

@@ -28,9 +28,9 @@ from fastapi.openapi.models import HTTPBearer
 from fastapi.openapi.models import OAuth2
 from fastapi.openapi.models import OpenIdConnect
 from fastapi.openapi.models import Schema
+import httpx
 from pydantic import BaseModel
 from pydantic import ValidationError
-import requests
 
 from ....auth.auth_credential import AuthCredential
 from ....auth.auth_credential import AuthCredentialTypes
@@ -289,14 +289,14 @@ def openid_url_to_scheme_credential(
   Raises:
       ValueError: If the OpenID URL is invalid, fetching fails, or required
         fields are missing.
-      requests.exceptions.RequestException:  If there's an error during the
+      httpx.HTTPStatusError or httpx.RequestError: If there's an error during the
           HTTP request.
   """
   try:
-    response = requests.get(openid_url, timeout=10)
+    response = httpx.get(openid_url, timeout=10)
     response.raise_for_status()
     config_dict = response.json()
-  except requests.exceptions.RequestException as e:
+  except httpx.RequestError as e:
     raise ValueError(
         f"Failed to fetch OpenID configuration from {openid_url}: {e}"
     ) from e

src/google/adk/tools/openapi_tool/openapi_spec_parser/rest_api_tool.py

@@ -28,7 +28,7 @@ from typing import Union
 from fastapi.openapi.models import Operation
 from fastapi.openapi.models import Schema
 from google.genai.types import FunctionDeclaration
-import requests
+import httpx
 from typing_extensions import override
 
 from ....agents.readonly_context import ReadonlyContext
@@ -312,7 +312,7 @@ class RestApiTool(BaseTool):
 
     Returns:
         A dictionary containing the  request parameters for the API call. This
-        initializes a requests.request() call.
+        initializes an httpx.AsyncClient.request() call.
 
     Example:
         self._prepare_request_params({"input_id": "test-id"})
@@ -497,17 +497,7 @@ class RestApiTool(BaseTool):
       if provider_headers:
         request_params.setdefault("headers", {}).update(provider_headers)
 
-    # Log the API request
-    self._logger.debug(
-        "API Request: %s %s",
-        request_params.get("method", "").upper(),
-        request_params.get("url", ""),
-    )
-    self._logger.debug("API Request params: %s", request_params.get("params"))
-    if "json" in request_params:
-      self._logger.debug("API Request body: %s", request_params.get("json"))
-
-    response = requests.request(**request_params)
+    response = await _request(**request_params)
 
     # Log the API response
     self._logger.debug(
@@ -519,11 +509,9 @@ class RestApiTool(BaseTool):
 
     # Parse API response
     try:
-      response.raise_for_status()  # Raise HTTPError for bad responses
-      result = response.json()  # Try to decode JSON
-      self._logger.debug("API Response body: %s", result)
-      return result
-    except requests.exceptions.HTTPError:
+      response.raise_for_status()  # Raise HTTPStatusError for bad responses
+      return response.json()  # Try to decode JSON
+    except httpx.HTTPStatusError:
       error_details = response.content.decode("utf-8")
       self._logger.warning(
           "API call failed for tool %s: Status %d - %s",
@@ -556,3 +544,10 @@ class RestApiTool(BaseTool):
         f' auth_scheme="{self.auth_scheme}",'
         f' auth_credential="{self.auth_credential}")'
     )
+
+
+async def _request(**request_params) -> httpx.Response:
+  async with httpx.AsyncClient(
+      verify=request_params.pop("verify", True)
+  ) as client:
+    return await client.request(**request_params)