Can it alert on a single new PR instead of a digest?

Yes. Run the agent more often and have it post one message per PR it hasn't seen, keeping a short list of the IDs it already announced so it doesn't repeat.

Does it need write access to GitHub?

No. It only reads with list_pull_requests, so a read-scoped token covers the GitHub side. The writing happens in Slack.

Why not use GitHub's own Slack app?

You can. This version earns its place when you want the agent to filter or summarize first, for example only PRs touching a directory you own, rather than every event on the repo.

GitHubSlack

Post GitHub pull request alerts to Slack

A GitHub + Slack agent flow

A pull request that sits unreviewed for two days is usually a pull request nobody noticed. This recipe puts your agent in charge of the noticing. It lists the open PRs on a repo with GitHub's list_pull_requests, filters for the ones still waiting on a human, and posts a short digest into a Slack channel with conversations_add_message. The review queue then shows up where your team already talks, instead of in a tab someone has to remember to open. Because the GitHub server answers a request rather than streaming events, the agent checks on the schedule you give it, and you set how loud it gets: a ping per new PR, or one morning summary of everything still open.

The flow

GitHublist_pull_requests

Lists pull requests in a repository with filters.

Slackconversations_add_message

Posts a message to a public channel, private channel, or DM.

Step by step

Pick the repo and the channel
Tell the agent which repository to watch and which channel gets the alerts, plus what needs review means for you: no reviewer assigned yet, or open past the age you care about. Both come straight off the list, where approval state does not.
List what's open
The agent calls list_pull_requests with a state filter and reads back the open PRs, their authors, and how long each has waited.
Post the digest
It formats one line per PR with title, author, and link, then sends the message to your channel with conversations_add_message.

Tell your agent

Every weekday at 9am, list the open pull requests on acme/api that have no reviewer assigned, and post them to #eng-reviews as a short list with title, author, age, and link. Skip drafts.

Setup

This flow needs both servers connected to your agent. Follow each install guide:

GitHub install guide Slack install guide

Worth knowing

conversations_add_message ships disabled by default on Slack's server. Turn it on, or the agent can read Slack but not post to it.
list_pull_requests returns drafts alongside ready PRs. Filter them out in the prompt unless you want drafts in the digest.
GitHub paginates its results. For a busy repo, tell the agent to read every page before it counts what's open, or the digest will run short.

Questions

Can it alert on a single new PR instead of a digest?: Yes. Run the agent more often and have it post one message per PR it hasn't seen, keeping a short list of the IDs it already announced so it doesn't repeat.
Does it need write access to GitHub?: No. It only reads with list_pull_requests, so a read-scoped token covers the GitHub side. The writing happens in Slack.
Why not use GitHub's own Slack app?: You can. This version earns its place when you want the agent to filter or summarize first, for example only PRs touching a directory you own, rather than every event on the repo.