Provide custom unfurl behavior for user-posted URLs

An MCP tool from the Slack API server, hosted on mcp.hjlabs.in.

Provide custom unfurl behavior for user-posted URLs [POST /chat.unfurl]

Name on the gateway: slack_api__chat_unfurl · may change things.

Parameters

Name	Type	Description
`channel` required	`string`	Channel ID of the message
`ts` required	`string`	Timestamp of the message to add unfurl behavior to.
`unfurls`	`string`	URL-encoded JSON map with keys set to URLs featured in the the message…
`user_auth_message`	`string`	Provide a simply-formatted string to send as an ephemeral message to the user…
`user_auth_required`	`boolean`	Set to true or 1 to indicate the user must install your Slack app to trigger…
`user_auth_url`	`string`	Send users to this custom URL where they will complete authentication in your…

Through the Smart Gateway, any client can run it by name with call_tool, or let the gateway find it with search_tools:

call_tool arguments

{
  "name": "slack_api__chat_unfurl",
  "arguments": {
    "channel": "…",
    "ts": "…"
  }
}

Or connect the Slack API server directly, which lists 174 tools including this one:

Run in your terminal

claude mcp add --transport http hj-slack-api https://mcp.hjlabs.in/mcp/slack-api \
  --header "Authorization: Bearer YOUR_API_KEY"

Use the provide custom unfurl behavior for user-posted urls tool with channel set to ….