slack_search_messages
Searches Slack messages across locally-cached channels using full-text substring matching. Only messages that Slack Desktop has synced to disk are searched — this is not the Slack cloud search API. Optionally restrict search to a specific channel_id.
This record as markdown: /tools/com-local-mcp-local-mcp/slack-search-messages.md
What slack_search_messages does on Local
AI agents call slack_search_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 results to return (default 50) |
query | string | Yes | Search text (case-insensitive substring match) |
channel_id | string | — | Optional channel ID to restrict search |
Parameters from the server's own tool schema.
Why slack_search_messages is rated Low
This tool retrieves and queries cached Slack message data without any side effects. It performs full-text substring matching and optional filtering by channel, which are classic read operations. No data is created, modified, deleted, or executed.
From the tool's definition Tool description explicitly states it 'Searches Slack messages' and 'Only messages that Slack Desktop has synced to disk are searched' — operations are read-only queries with no modification, deletion, or execution capabilities.
Attacks that exploit this kind of access
The rule that runs slack_search_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 slack_search_messages, this is the rule to start with:
slack_search_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 slack_search_messages call is checked against it from then on.
Questions about slack_search_messages
Searches Slack messages across locally-cached channels using full-text substring matching. Only messages that Slack Desktop has synced to disk are searched — this is not the Slack cloud search API. Optionally restrict search to a specific channel_id. It is categorised as a Read tool in the Local MCP Server, which means it retrieves data without modifying state.
slack_search_messages accepts 3 parameters: limit, query, channel_id. Required: query. 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 slack_search_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.
slack_search_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 slack_search_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 slack_search_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.
slack_search_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.
More on Local, and thousands of servers like it.
This server
Across the catalogue