Improvements for handling in-page tool responses. In order to
successfully pass an in-page tool response from the page context to the
MCP server, the response needs to be serializable. The code walks the
response object an performs the following changes:
- DOM elements are stashed onto the window object and replaced with an
ID. On the MCP server side this ID is used to map back to the
corresponding UID in the page snapshot generated from the accessibility
tree.
- Circular references are replaced with a string.
- Class instances (which can be complex or non-serializable) are
replaced with a string.
- Functions are replaced with a string.
If the in-page tool response contains DOM elements which are not part of
the page snapshot, a new snapshot is created add the missing elements
are added explicitly.
The idea is to turn formatters into instances and support both text and
JSON formatting. The structured content is output if the experimental
structured content flag is passed. For now, only the snapshots are
returned in a structured way.
Refs https://github.com/ChromeDevTools/chrome-devtools-mcp/issues/689
Alex Rudenko