Signal MCP vs Justcall MCP Server

edit_message

Edit the text of a previously sent message. Sends the edit via signal-cli to all original recipients; they see the updated text inline with an '(edited)' label. Only the message text can be modified — attachments, quoted replies, and reactions are immutable. The edit must reference the exact timestamp of the original message as returned by send_message or get_conversation. Edits can only be made to messages you sent; editing someone else's message returns an error. There is no enforced time limit, but Signal clients may ignore edits on very old messages. Provide recipient for a DM edit or group_id for a group edit; exactly one is required. Use when correcting a typo or updating information in a message you already sent. Do NOT use to change who a message was sent to — send a new message instead.

receive_messages

Manually poll signal-cli for new messages and store them. Prefer get_unread — it does this automatically and returns results in one call. Use receive_messages only if you want to poll without reading results.

receive_direct

Receive messages by calling signal-cli directly, bypassing the daemon. Use this as a fallback when the daemon is stuck or unresponsive — it stops the daemon, calls signal-cli receive directly, then lets the daemon restart. Prefer receive_messages (daemon mode) for normal use; use this only for troubleshooting.

list_contacts

List all Signal contacts known to this account, including names and phone numbers. Use the optional search parameter to filter by name or number substring. Returns contacts from signal-cli's local contact store. Use get_profile to fetch the current Signal profile for a specific contact.

list_groups

List all Signal groups this account belongs to, including group name, ID, members, and admin list. The group_id returned here is required for send_group_message, send_group_attachment, and update_group. Use update_group to modify a group, or leave_group to exit.

get_conversation

Get recent message history with a contact or group from local store. Automatically marks returned messages as read in the local store (does NOT send a Signal read receipt — call send_read_receipt for that).

search_messages

Full-text search across all locally stored messages by keyword or phrase. Searches message bodies using SQLite FTS — results are ranked by relevance. Only messages in the local store are searchable; messages never received on this device are excluded. Use sender to narrow results to a specific conversation. Use limit and offset to paginate through large result sets. Use when looking for a specific message or topic across all Signal conversations. Do NOT use to browse a conversation chronologically — use get_conversation for that.

send_attachment

Send one or more files or images to a Signal contact. Supports photos, videos, documents, and audio files. Use path for a single file or paths to send multiple files in one message. Set view_once=true to send media that auto-deletes after the recipient views it once. For groups use send_group_attachment instead.

send_group_attachment

Send one or more files (photos, videos, documents, audio) to a Signal group in a single message. All current group members receive the attachment via the normal Signal encrypted delivery pipeline. Provide path for a single file or paths for multiple files sent together in one message. Set view_once=true so each member can only open the media once before it disappears — ideal for sensitive images; does not apply to document types. The file must exist and be readable on the local filesystem; non-existent paths return an error. Use list_groups to obtain the group_id. Use when sharing a file with a group chat. Do NOT use for direct messages — use send_attachment instead. Do NOT use when you only want to send text — use send_group_message instead.