Answer questions when someone mentions your agent in Slack

This recipe builds an agent that answers when someone mentions it in a Slack channel. It replies in the message’s thread, and reads the thread when it’s mentioned again there. The agent answers from your workspace context, so you control what it knows without changing the agent.

Before you start

The Guild CLI, logged in.
Slack connected in your workspace. See Slack setup.
The Slack agent invited to the channels where it should reply. It posts with the chat:write scope, which only reaches channels it belongs to.

1. Create the agent

guild agent init --name slack-helper --agent-type GUILD_NATIVE
cd slack-helper

Replace PROMPT.md:

You answer questions people ask in Slack.

Your input is a Slack app_mention event. The question is in event.text,
the channel is event.channel, and the message timestamp is event.ts.

If event.thread_ts is set, read the thread first with
slack_conversations_replies, using channel event.channel and ts
event.thread_ts, so you know what was said before.

Answer from the workspace context. If it doesn't cover the question, say
you don't know and suggest who might.

Reply with slack_chat_post_message in the thread: set channel to
event.channel, and thread_ts to event.thread_ts if it is set, otherwise
event.ts. Keep replies under 150 words.

Replace guild.yaml:

integrations:
  - name: guildai~slack
    version: ^2.0.0
    tools:
      - slack_chat_post_message
      - slack_conversations_replies

2. Give it something to answer from

Add your team’s facts to the workspace context: on-call rotation, where runbooks live, how to request access, release days. Open the workspace, click Context, write in Markdown, and publish. See Workspace context.

3. Save it and install it in your workspace

guild agent save --message "First version" --publish
guild workspace agent add <your-name>~slack-helper

4. Create the trigger

guild trigger create \
  --type webhook \
  --integration slack \
  --event app_mention \
  --agent <your-name>~slack-helper \
  --service-config '{"channel_ids": ["<channel-id>"]}' \
  --name "Answer Slack mentions"

channel_ids limits the trigger to the channels you list. Find a channel’s ID at the bottom of its details in Slack. Omit --service-config to answer in every channel. Slack events have no actions, so there’s no --action. The agent receives a prompt that names the event, followed by the Slack payload as JSON, trimmed to the fields an agent needs.

5. Try it

In the channel, mention the Slack agent with a question the context answers. The reply appears in the thread, with a link to the Guild session underneath. To ask a follow-up, mention it again in the same thread. Each mention is a new run in the thread’s session; the agent reads the thread with slack_conversations_replies to see the earlier exchange. A reply in the thread that doesn’t mention the agent doesn’t trigger it.

How the run is attributed

If the person who mentioned the agent has an identity mapping, the run acts as their Guild user. Otherwise it acts as the trigger’s creator. Messages always post as the Slack agent.

Variations

Answer direct messages too. Create a second trigger on message with no channel_ids. It also fires on every message in channels the agent belongs to, so tell the agent to reply only when event.channel_type is im. See Direct messages.
Look things up before answering. Add another integration’s read tools to guild.yaml, such as jira_get_issue, so the agent can answer “what’s the status of ENG-123?”.

Slack integration: events, scopes, and how sessions work
Event triggers: agent input and service_config
Native agents: what a prompt-only agent can and can’t do

Overview

The Smith

The Factory

Platform

Agent SDK

Answer questions when someone mentions your agent in Slack

Before you start

1. Create the agent

2. Give it something to answer from

3. Save it and install it in your workspace

4. Create the trigger

5. Try it

How the run is attributed

Variations

​Before you start

​1. Create the agent

​2. Give it something to answer from

​3. Save it and install it in your workspace

​4. Create the trigger

​5. Try it

​How the run is attributed

​Variations

​Related

Before you start

1. Create the agent

2. Give it something to answer from

3. Save it and install it in your workspace

4. Create the trigger

5. Try it

How the run is attributed

Variations

Related