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Can an AI assistant read and send your Signal messages?

Last updated 2026-08-21 · Confidence: documented — the bridge projects’ READMEs, Signal’s blog, and Anthropic’s help center; “no official Signal API” is inferred from the server README and connector directory, and the terms-enforcement question is unverified either way.

Not through any official channel — Signal has no connector in Claude’s directory and no public API — but unofficial signal-cli-based MCP servers can join your account as a linked device to send messages and read new ones. Old messages only come along by importing Signal Desktop’s local database.

No official route

Section titled “No official route”

Anthropic’s connector directory lists no Signal — no messaging apps at all. Signal itself offers no API for personal accounts: the Signal-Server README points only to protocol docs and an unofficial community forum.

The bridge: signal-cli as a linked device

Section titled “The bridge: signal-cli as a linked device”

signal-cli links to your account the way Signal Desktop does — a QR scan under Settings → Linked devices — and can send and receive; signal-cli-rest-api wraps it as a dockerized REST API. MCP servers build on it: signal-mcp runs a background service that stores every incoming message in a searchable local SQLite database, with tools for conversations, search, sending, and attachments.

The catch: linking starts empty

Section titled “The catch: linking starts empty”

Signal’s synchronized-start feature (2025) transfers chats plus 45 days of media to newly linked official devices — but signal-cli hasn’t implemented it, so a bridge sees only messages arriving after linking, plus contacts and groups. For history, a read-only MCP server reads Signal Desktop’s local database directly instead — whatever Desktop already holds, no sending.

Where it runs, and the risks

Section titled “Where it runs, and the risks”

The bridge is a local process: claude.ai and Cowork take only remote connector URLs, so it needs Claude Code or Claude Desktop. Same caution as WhatsApp access: Signal’s terms bar using the service “in unauthorized manners” without naming third-party clients, and an agent holding your messages plus a send tool warrants approvals on sends — see Agent safeguards.

Sources

Section titled “Sources”