Slack Web API

Can I post messages with rich formatting using the Slack Web API?

Yes. The chat.postMessage endpoint accepts a blocks array using Slack's Block Kit format. You can include sections with markdown text, images, buttons, select menus, and dividers. Alternatively, use the text parameter with Slack's mrkdwn syntax for simpler formatting. The blocks array supports up to 50 blocks per message.

What are the rate limits for the Slack Web API?

Slack uses tiered rate limiting. Most methods allow 1 request per second (Tier 2) or 50+ per minute (Tier 3). chat.postMessage allows about 1 message per second per channel. Responses include Retry-After headers when limits are exceeded. Web API methods are classified into tiers 1-4 with increasing generosity.

How do I search for messages across channels through Jentic?

Search Jentic for 'search Slack messages'. Jentic returns the GET /search.messages endpoint schema with query, sort, and sort_dir parameters. The query parameter supports Slack search modifiers like 'from:@user', 'in:#channel', 'before:2026-05-01'. Load the schema, set your query, and execute to get paginated results.

Can I create channels and manage membership via the API?

Yes. Use conversations.create with a name and is_private flag to create channels. Then conversations.invite adds users by their user IDs. conversations.setTopic and conversations.setPurpose configure the channel metadata. conversations.kick removes members, and conversations.archive retires unused channels.

How do I upload files to Slack channels?

Use the two-step upload flow: first call files.getUploadURLExternal to get a presigned upload URL and file_id, then upload the binary data to that URL, and finally call files.completeUploadExternal with the file_id and channel_id to publish it. This replaced the older files.upload endpoint and supports files up to 1GB.

Can I limit what my agent is allowed to do with the Slack Web API?

Yes. Because you run Jentic One yourself, you decide which Slack operations your agent may call, so you can allow only what it needs, such as chat.postMessage for posting or conversations.history for reading a channel. Slack passes the channel in the request body rather than a resource id in the path, so scoping is done at the operation level rather than per channel. Operations like conversations.create or conversations.invite stay out of the allowed set unless you explicitly add them, and the OAuth token your instance holds is injected at execution time without ever reaching the agent's prompt or logs.