slack_post_message
Post a new message to a Slack channel
Part of the Slack MCP server. Enforce policies on this tool with Intercept, the open-source MCP proxy.
WHEN AI AGENTS USE THIS TOOL
AI agents use slack_post_message to create or modify resources in Slack. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
WHY ENFORCE A POLICY ON SLACK_POST_MESSAGE
Without a policy, an AI agent could call slack_post_message repeatedly, creating or modifying resources faster than any human could review. Intercept's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Slack.
RECOMMENDED POLICY
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
tools:
slack_post_message:
rules:
- action: allow
rate_limit:
max: 30
window: 60See the full Slack policy for all 8 tools.
DETAILS
MORE SLACK TOOLS
slack_add_reaction Write slack_get_channel_history Read slack_get_thread_replies Read slack_get_user_profile Read slack_get_users Read slack_list_channels Read slack_reply_to_thread Other SIMILAR WRITE TOOLS ON OTHER SERVERS
RELATED READING
FREQUENTLY ASKED QUESTIONS
What does the slack_post_message tool do?
Post a new message to a Slack channel. It is categorised as a Write tool in the Slack MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
How do I enforce a policy on slack_post_message?
Add a rule in your Intercept YAML policy under the tools section for slack_post_message. You can allow, deny, rate-limit, or validate arguments. Then run Intercept as a proxy in front of the Slack MCP server.
What risk level is slack_post_message?
slack_post_message is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Can I rate-limit slack_post_message?
Yes. Add a rate_limit block to the slack_post_message rule in your Intercept 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.
How do I block slack_post_message completely?
Set action: deny in the Intercept policy for slack_post_message. 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.
What MCP server provides slack_post_message?
slack_post_message is provided by the Slack MCP server (modelcontextprotocol/server-slack). Intercept sits as a proxy in front of this server to enforce policies before tool calls reach the server.
ENFORCE POLICIES ON SLACK
Open source. One binary. Zero dependencies.