[Jae Bird (jaeminbird)]

Motivation and Context

MCP sends image/audio data and blob blob as base64, but the MCP connector builds ImageContent/AudioContent/BinaryContent without data_format="base64". So .data holds the base64 text, data_uri becomes data:image/png;,iVBOR... (no ;base64), and blob resources lose their mimeType (text/plain). Tool results, prompts and sampling messages with images reach the model broken; the Google AI connector sends the base64 text as image bytes.

Description

Pass data_format="base64" for the three types, and the resource mimeType for blobs.

• New test covers image, audio and a blob resource via call_tool and get_prompt; fails before, passes after.
• urllib.request.urlopen(content.data_uri) now returns the original bytes (before: the base64 text).
• tests/unit/connectors/mcp and tests/unit/contents pass; ruff and mypy clean.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

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[Jae Bird (jaeminbird)]

@microsoft-github-policy-service agree