Google Chat: Manage message reactions — MCP tool

Google Chat MCP tool: Adds, lists and removes emoji reactions on a message as the authenticated user.

Technical name: manage_reactions

What task it solves

I want to react to a Google Chat message with an emoji, or see who reacted.

One tool with an action switch: add puts a unicode emoji on a message, list shows each reaction with its name/emoji/user, remove deletes one of the caller's own reactions.

When to use it

Use add to acknowledge a message (👍, 🎉), list to count votes or find your reaction's name, and remove to take a reaction back.

What to provide

• action — required. add, list or remove.
• message — add/list. The full message name.
• emoji — add: the emoji character itself (e.g. "👍", not :thumbsup:); list: optional filter.
• reaction_name — remove. The full reaction name from action=list.
• page_size, page_token — list pagination.

What it returns

add returns the created reaction; list a page of reactions; remove an empty object.

What changes in Google Chat

add attaches a visible reaction under the user's name and remove deletes one; list reads without changing anything. Removal is destructive — the reaction is gone for everyone.

Example request

Add a 🎉 reaction to the release announcement message in spaces/AAAAAAAAAAA.

Errors and limitations

Adding the same emoji twice fails with ALREADY_EXISTS. Only the authenticated user's own reactions can be removed — someone else's returns PERMISSION_DENIED. Custom (workspace) emoji need raw_request with emoji.customEmoji. Scopes: chat.messages.reactions (add/remove) or chat.messages.reactions.readonly (list).

Related MCP tools

• Get a message — get_message
• List messages — list_messages
• Raw Google Chat API call — raw_request

Technical details

• Impact: destructive operation
• Group: Reactions
• Description source: manage_reactions registration in src/tools/reactions.ts
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