Add a reaction emoji to a message. Use standard unicode emoji or custom emoji in name:id format.
AI agents use discord_react to create or update resources in Discord User — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Discord User environment.
Adding a reaction is a reversible modification of message metadata (the reaction can be removed). It does not delete data (ruling out Destructive), execute code (ruling out Execute), or involve financial transactions (ruling out Financial). It creates/modifies Discord message reactions, fitting the Write category.
From the tool's definition Tool description: 'Add a reaction emoji to a message' — this creates a new reaction object on an existing message, modifying message state.
Documented attack patterns abuse exactly the kind of access discord_react gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Discord User, and nothing reaches the server without passing your rules. This is the rule we recommend for discord_react:
{
"version": "1",
"default": "deny",
"tools": {
"discord_react": {
"limits": [
{
"counter": "discord_react_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}discord_react stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
Free to start. No card required.
Add a reaction emoji to a message. Use standard unicode emoji or custom emoji in name:id format. It is categorised as a Write tool in the Discord User MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Discord User MCP server in PolicyLayer and add a rule for discord_react: 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 Discord User. Nothing to install.
discord_react is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the discord_react 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 discord_react. 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.
discord_react is provided by the Discord User MCP server (olivier-motium/discord-user-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Discord User, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
16 Discord User tools catalogued and risk-classified — across an index of 43,000+ MCP servers.