signal_read_messages
Reads messages from a specific Signal chat. The chat_id must come from a previous signal_list_chats call. Returns messages in chronological order with sender phone numbers and body text. Only messages cached locally by Signal Desktop are available.
This record as markdown: /tools/com-local-mcp-local-mcp/signal-read-messages.md
What signal_read_messages does on Local
AI agents call signal_read_messages to retrieve information from Local without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
limit | integer | — | Max messages to return (default 50) |
chat_id | string | Yes | Chat ID from signal_list_chats |
Parameters from the server's own tool schema.
Why signal_read_messages is rated Low
This is a read operation that retrieves cached Signal messages locally. While the category is Read (no side effects), the severity is high because Signal messages often contain sensitive personal communications, authentication codes, and private data. Unauthorized access by a compromised AI agent could expose significant personal information, even though the operation itself is non-destructive.
From the tool's definition Tool name 'signal_read_messages' and description explicitly states it 'Reads messages from a specific Signal chat' and 'Returns messages in chronological order with sender phone numbers and body text.' No modification, deletion, or execution capability is…
Attacks that exploit this kind of access
The rule that runs signal_read_messages safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Local, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For signal_read_messages, this is the rule to start with:
signal_read_messages is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Local, apply this rule, and every signal_read_messages call is checked against it from then on.
Questions about signal_read_messages
Reads messages from a specific Signal chat. The chat_id must come from a previous signal_list_chats call. Returns messages in chronological order with sender phone numbers and body text. Only messages cached locally by Signal Desktop are available. It is categorised as a Read tool in the Local MCP Server, which means it retrieves data without modifying state.
signal_read_messages accepts 2 parameters: limit, chat_id. Required: chat_id. The full parameter table on this page comes from the server's own tool schema.
Register the Local MCP server in PolicyLayer and add a rule for signal_read_messages: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Local. Nothing to install.
signal_read_messages is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the signal_read_messages rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for signal_read_messages. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
signal_read_messages is provided by the Local MCP server (local-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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