feat-add-reactions

[xav-ie]

You can now add emoji reaction through MCP 👍

I consider emoji as a message, so I leverage the existing env var. Please let me know if I should have instead created a new one.

• feat: add reaction tool

[korotovsky]

Hi @xav-ie, thanks for the PR!

There is somehow a demand for this feature, so that's why I come here across. Could you please confirm that this functionality works on all three types of tokes? xoxc/xoxd, xoxp and xoxb ? Which one have you tested so far?

[ZihaoZhou]

Tested. Working perfectly with xoxp. Needs reactions.write permission.

[xav-ie]

Hello, I use xoxc and xoxd. I am glad to hear others who use got it working with xoxp, too. I think it is sufficient to take Zihao at their word for the xoxp functioning.

For xoxb, I see that Slack apps have this permission:

I see no reason why the API call would fail.

[korotovsky]

I'd appreciate that before we merge @xav-ie or @ZihaoZhou will do one more test with xoxb as well, because this MCP has lots of users, and since this PR comes without extra integration tests, then in my opinion at least full manual testing must be done beforehand.

[xav-ie]

Yes ok. That is reasonable. It would be cool to fully automate the testing. Like have a ci and functions to test things. I might make one after I verify this works with xoxb.... verifying all three for api changes is quite a bit of work.

[korotovsky]

@xav-ie please have a look an existing implementation of integration tests i.e. how MCP server is bootstrapped, tools registered and how we verify that using real OpenAI API this MCP is truly working https://github.com/korotovsky/slack-mcp-server/blob/master/pkg/handler/channels_test.go#L31. I might need then to add a new xoxb secret variable from my workspace into this repository, but we will get there later. At the current point would be nice it you would setup entire integration stack locally if you are planning to improve it.

[Flare576]

✅ Tested with xoxb (Bot Token) - Works!

I set up a test workspace specifically to verify this PR with bot tokens. Full test results:

Test Environment

• Workspace: flare-testgrounds.slack.com (created for this test)
• Token type: xoxb-* (Bot OAuth Token)
• MCP Server: Built from this branch via Docker
• Transport: stdio

Test Procedure

1. Built Docker image from feat-add-reactions branch
2. Initialized MCP server with SLACK_MCP_XOXB_TOKEN
3. Posted a test message via conversations_add_message
4. Called reactions_add with 3 different emojis

Results

Emoji	Result
:rocket:	✅ Success
:tada:	✅ Success
:white_check_mark:	✅ Success

MCP Response Examples

{"result": {"content": [{"type": "text", "text": "Successfully added :rocket: reaction to message 1769718633.771359 in channel C0ABNAGCV19"}]}}
{"result": {"content": [{"type": "text", "text": "Successfully added :tada: reaction to message 1769718633.771359 in channel C0ABNAGCV19"}]}}
{"result": {"content": [{"type": "text", "text": "Successfully added :white_check_mark: reaction to message 1769718633.771359 in channel C0ABNAGCV19"}]}}

Slack Verification

Verified reactions appear correctly in Slack UI:

---

This completes testing for all three token types:

• xoxc + xoxd (browser tokens) - tested by @xav-ie
• xoxp (user token) - tested by @xav-ie
• xoxb (bot token) - tested here ✅

Ready to merge! 🚀

[korotovsky]

This is the way to go! 🚀 Thank you @Flare576!

Thank you @ZihaoZhou for testing xoxp and @xav-ie for PR itself.