Liveness check — returns "pong" if the server is running.

List configured ProtonMail accounts (never includes credentials).

List folders with message and unread counts. ProtonMail labels appear as folders under Labels/, custom folders under Folders/.

List emails in a folder, newest first, with pagination and date/sender/unread filters (dates are ISO YYYY-MM-DD). To list emails carrying a ProtonMail label, pass mailbox="Labels/".

Read one email in full: body (text preferred), headers, threading ids, and attachment metadata.

Search a folder by keyword across subject, sender, and body.

Reconstruct the conversation thread around an email via its Message-ID / References headers (within the given folder).

Download one attachment (base64), capped at 5 MB.

Send a new email through Bridge. Bridge files it into Sent.

Reply to an email with correct threading (In-Reply-To/References) so the conversation stays intact in ProtonMail.

Forward an email with the original content quoted.

Save an email as a draft in the Drafts folder without sending.

Move an email to another folder.

Delete an email: moves it to Trash unless permanent=true. Refused on the virtual All Mail folder.

Mark an email read/unread and/or flagged/unflagged.

Create a folder. Bare names are created under ProtonMail's Folders/ namespace; pass an explicit Folders/... or Labels/... path to control placement.

List ProtonMail labels. Labels are IMAP folders under Labels/ — use list_emails with mailbox="Labels/" to see tagged mail.

Add a ProtonMail label to an email (copies it into the Labels/ folder — that is how Bridge represents labels).

Remove a ProtonMail label from an email (deletes its copy from the Labels/ folder, located by Message-ID).

Create a new ProtonMail label (a folder under Labels/).

Delete a ProtonMail label (removes the Labels/ folder).

Report on the local ProtonMail Bridge: installed, running, ports, certificate, and configured accounts.

Check IMAP and SMTP connectivity (with latency) for one account or all of them. Returns guidance instead of failing when Bridge is down.