Add markdown output support

[adarshdigievo]

Summary

Search results can now be returned as Markdown by setting params.output to "md". JSON remains the default for this release, so existing clients keep the same behavior.

Changes

• Added optional Markdown responses through params.output="md".
• Kept omitted and explicit output="json" requests as JSON.
• Kept MCP Apps on JSON by overriding their internal requests with output="json".
• Documented Markdown output and added examples for Amazon, Google Scholar, YouTube, Apple App Store, and eBay.
• Bumped the feature version from 0.5.0 to 0.6.0.
• Currently, mode=compact keeps markdown unaltered.

Fixes

Previously, passing an output=html param to tool requests caused an .as_dict() conversion error because the SDK returned raw HTML as a string. This is now clearly shown as a format error:

The search tool now accepts only "json" and "md". Other values are rejected before the request with:

Error: Invalid output. Use either 'md' or 'json' for the output parameter.

Testing

• Verified MCP Apps, search tool, and resource docs via MCP Inspector. Default requests use JSON and work.
• "output": "md" result:

Request:

Response:

Response from Amazon engine: