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Adds a reaction to an item.

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

Adds a reaction to an item. [POST /reactions.add]

Name on the gateway: slack_api__reactions_add · may change things.

Parameters

Name	Type	Description
`channel` required	`string`	Channel where the message to add reaction to was posted.
`name` required	`string`	Reaction (emoji) name.
`timestamp` required	`string`	Timestamp of the message to add reaction to.

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__reactions_add",
  "arguments": {
    "channel": "…",
    "name": "…",
    "timestamp": "…"
  }
}

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 adds a reaction to an item. tool with channel set to ….