[Release] google/adk-python v1.21.0: Release 1.21.0

Google ADK Python v1.21.0 introduces support for the Gemini Interactions API, enhances tools with header providers and SSL verification, upgrades BigQueryAgentAnalytics to v2.0, and adds Gemma3Ollama model integration. The release includes numerous bug fixes for LiteLLM response formatting, Spanner client initialization, OpenAPI schema generation, and security updates for FastAPI/Starlette vulnerabilities.

Key Points

• •Enable Gemini Interactions API support in ADK by setting `use_interactions_api=True` in the Gemini model configuration for enhanced agent capabilities
• •Add explicit session memory management using `add_session_to_memory` in CallbackContext and ToolContext for better state persistence
• •Upgrade BigQueryAgentAnalyticsPlugin to v2.0 with improved performance, multimodal support, and reliability; includes location tracking for agent events
• •Enhance OpenAPI tools with `header_provider` parameter, SSL certificate verification via `verify` parameter, and connection template overrides
• •Implement JSON schema-based function tool declarations for improved schema generation and compatibility with multiple LLM providers
• •Add Gemma3Ollama model integration and normalize multipart content handling for LiteLLM's ollama_chat provider
• •Support ADK EventActions in A2A responses and improve error handling with proper HTTP error codes and task_id propagation
• •Fix critical security vulnerability (CVE-2025-62727 ReDoS) by updating FastAPI and Starlette dependencies
• •Improve tool naming with `tool_name_prefix` support in OpenAPIToolset and enhance context passing to client interceptors
• •Enhance Spanner query execution with dictionary-based result mode and improve error messaging for async operations

Workflow Diagram

Concepts

Artifacts (1)

Agent(
  model=Gemini(
      model="gemini-3-pro-preview",
      use_interactions_api=True,
  ),
  name="...",
  description="...",
  instruction="...",
)