Gmail MCP: read_email does not return CC/BCC headers

Summary

mcp__gmail__read_email returns From, To, Date, and Subject headers, but omits CC and BCC entirely. This makes it impossible to implement reply-all workflows where CC recipients need to be carried over to draft replies.

Reproduction

1. Find an email with CC recipients using mcp__gmail__search_emails with query cc:user@example.com
2. Read the email using mcp__gmail__read_email with the returned message ID
3. Observe that the output contains only From, To, Date, Subject — no CC or BCC field

Evidence

Tested with 4 emails confirmed to have CC recipients (found via cc: search query). All 4 returned no CC information from read_email.

| Email | Found via cc: search | read_email output |
|-------|---------------------|-------------------|
| Email 1 | ✅ | From/To only, no CC |
| Email 2 | ✅ | From/To only, no CC |
| Email 3 | ✅ | From/To only, no CC |
| Email 4 | ✅ | From/To only, no CC |

Impact

• Cannot implement "reply-all" by carrying over CC recipients to mcp__gmail__draft_email
• Workaround requires calling Gmail API directly via google-api-python-client to fetch CC headers, which defeats the purpose of having an MCP integration

Request

Please include CC and BCC fields in the read_email response output.