Upload Attachment
mailbox_upload_attachmentUpload an attachment file for use when sending an email. Supports local file path, presigned URL, or inline base64 as a last resort.
Instructions
Use this before sending a mailbox attachment. Cheapest mode: file_path on local stdio MCP reads the user-approved local file without putting bytes in model context. Hosted or shell-capable agents should set presign_upload_url=true with filename, content_type, and size_bytes, then PUT the file to the returned short-lived URL promptly and send the returned blob_id. Inline content_base64 is a last resort for tiny agent-authored files only and is capped at 32 KiB decoded.
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| filename | Yes | Filename to use when sending the uploaded attachment. | |
| file_path | No | Local file path for stdio MCP only. The path must be inside a client-declared MCP root; hosted MCP rejects it. | |
| mailbox_id | No | Mailbox public ID when the credential can access more than one mailbox. | |
| size_bytes | No | Exact byte size required when presign_upload_url=true. | |
| content_type | No | MIME type to store with the upload, for example application/pdf. | application/octet-stream |
| content_base64 | No | Last-resort inline base64 for tiny agent-authored files only. Decoded content must be at most 32 KiB; use file_path or presign_upload_url for real files. | |
| presign_upload_url | No | When true, return a short-lived signed PUT URL instead of reading bytes. Provide size_bytes and upload with a shell/client promptly. |
Output Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||