143 tools. 71 can modify or destroy data without limits.
16 destructive tools with no built-in limits. Policy required.
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Destructive tools (SLACK_CLEAR_STATUS, SLACK_CUSTOMIZE_URL_UNFURL, SLACK_DELETE_A_COMMENT_ON_A_FILE) permanently delete resources. There is no undo. An agent calling these in a retry loop causes irreversible damage.
Write operations (SLACK_ACTIVATE_OR_MODIFY_DO_NOT_DISTURB_DURATION, SLACK_ADD_A_CUSTOM_EMOJI_TO_A_SLACK_TEAM, SLACK_ADD_A_REMOTE_FILE_FROM_A_SERVICE) modify state. Without rate limits, an agent can make hundreds of changes in seconds — faster than any human can review or revert.
Execute tools (SLACK_REGISTERS_A_NEW_CALL_WITH_PARTICIPANTS, SLACK_REGISTERS_NEW_CALL_PARTICIPANTS, SLACK_START_CALL) trigger processes with side effects. Builds, notifications, workflows — all fired without throttling.
Intercept sits between your agent and Slack. Every tool call checked against your policy before it executes — so your agent can do its job without breaking things.
npx -y @policylayer/intercept scan -- npx -y @modelcontextprotocol/server-slack SLACK_CLEAR_STATUS:
rules:
- action: deny Destructive tools should never be available to autonomous agents without human approval.
SLACK_ACTIVATE_OR_MODIFY_DO_NOT_DISTURB_DURATION:
rules:
- rate_limit: 30/hour Prevents bulk unintended modifications from agents caught in loops.
Returns:
rules:
- rate_limit: 60/minute Controls API costs and prevents retry loops from exhausting upstream rate limits.
Yes. The Slack server exposes 16 destructive tools including SLACK_CLEAR_STATUS, SLACK_CUSTOMIZE_URL_UNFURL, SLACK_DELETE_A_COMMENT_ON_A_FILE. These permanently remove resources with no undo. Intercept blocks destructive tools by default so they never reach the upstream server.
The Slack server has 51 write tools including SLACK_ACTIVATE_OR_MODIFY_DO_NOT_DISTURB_DURATION, SLACK_ADD_A_CUSTOM_EMOJI_TO_A_SLACK_TEAM, SLACK_ADD_A_REMOTE_FILE_FROM_A_SERVICE. Set rate limits in your policy file -- for example, rate_limit: 10/hour prevents an agent from making more than 10 modifications per hour. Intercept enforces this at the transport layer.
143 tools across 4 categories: Destructive, Execute, Read, Write. 72 are read-only. 71 can modify, create, or delete data.
One line change. Instead of running the Slack server directly, prefix it with Intercept: intercept -c slack.yaml -- npx -y @@modelcontextprotocol/server-slack. Download a pre-built policy from policylayer.com/policies/slack and adjust the limits to match your use case.
Starter policies available for each. Same risk classification, same one-command setup.
Set budgets, approvals, and hard limits across MCP servers.
npx -y @policylayer/intercept init