Description
Please make sure you read the contribution guide and file the issues in the right place.
Contribution guide
Is your feature request related to a problem? Please describe.
When building agents that include working with signed URLs (e.g., image generation agents that generate an image, upload image to a bucket, return a response after embedding the signed link), I ran into these problems:
- The LLM often breaks or alters the URLs (truncation, formatting changes).
- Sensitive URLs are unnecessarily exposed to the LLM, creating privacy and security concerns.
- Developers have to write repetitive custom logic to mask and unmask links.
Describe the solution you'd like
A standard ADK utility or base agent class that handles this pattern cleanly:
class LinkInjectorAgent(Agent):
"""
An agent that registers two callbacks:
1. After tool callback: extracts URLs, stores the URL-to-identifier mapping in
the state, and replaces the URLs with identifiers.
2. After model callback: restores URLs from identifiers mapping after
the LLM response is generated. Returns this modified response.
"""Example:
Tool response:
Image URL: https://storage.googleapis.com/bucket/...
(After replacing URL with link identifier):
Image URL: <link-a2c4-1>
LLM can then generate the response using the identifier:
Here is your image: [View](<link-a2c4-1>)
Final output (After replacing identifier with url):
Here is your image: [View](https://storage.googleapis.com/bucket/...)
I’ve implemented this in my project and found it effective and reliable. It would benefit from being part of ADK as a standard pattern.
Describe alternatives you've considered
- Letting LLM handle raw URLs (creates security and integrity risks).
- Storing all URL mappings in a temporary JSON file and retrieving as needed (can become complex when dealing with multiple sessions).
- Building a URL shortener with automatic expiration.
- Instructing the LLM to refer to resources as url_1, url_2, etc., without including links - requires extra post-processing to attach URLs later.
Additional context
- Ideal for agents working with signed URLs, tokenized URLs, or other temporary user-specific links (e.g., images, files, charts), where secure handling of URLs is critical.
- This could be added as a utility or as part of ADK agents.
I am interested in working on this feature and can provide implementation if accepted. (since I have already implemented a working version of this concept in my project)