Can an AI agent post to Slack?

Yes. Connect Slack in Mynahcast, give your agent an Agent API key, and it can draft and schedule Slack posts through the MCP server (https://api.mynahcast.xyz/mcp) or the REST API. Each post waits for your approval before it goes out.

How do I post to Slack with an API?

Send POST https://api.mynahcast.xyz/v1/posts with your API key as a bearer token, the brand id, the post body and your Slack channel id as a target. Add an Idempotency-Key header so a retry never posts twice.

What is the character limit for Slack posts in Mynahcast?

Up to 40,000 characters per post. Mynahcast checks the limit before saving, so an agent finds out at validation time, not at publish time.

Is posting to Slack with Mynahcast free?

Every Mynahcast plan includes every live channel, from $12 per month (5 channels) with a 7-day free trial.

Live

Slack

Posts land in one channel through an incoming webhook.

What it supports

Up to 40,000 characters per post, with formatting.
Text only (no media uploads on this channel yet).
The platform returns no post id, so Mynahcast trusts its success response (it can't read the post back).
Approvals, scheduling and one-time delivery work the same as on every other channel.

How to connect

In Mynahcast: Channels → Add channel → Slack.

Incoming webhook

1Open https://api.slack.com/apps → Create New App → From scratch, pick your workspace.
2Incoming Webhooks → turn on → Add New Webhook to Workspace → choose the channel → Allow.
3Copy the webhook URL (https://hooks.slack.com/services/…) and paste it in Mynahcast.

You'll paste

Webhook URL

Credentials are encrypted before they're stored and never shown again. Disconnect any time from the Channels page.

Post to Slack from your AI agent

Once Slack is connected, any agent with a Mynahcast key can target it: Claude Code, Cursor and other MCP clients through mynahcast_create_post, ChatGPT through a GPT action, or your own code through the REST API. Connect your agent.

REST: schedule a Slack post

curl -X POST "https://api.mynahcast.xyz/v1/posts" \
  -H "Authorization: Bearer $MYNAHCAST_KEY" \
  -H "Idempotency-Key: slack-001" \
  -H "Content-Type: application/json" \
  -d '{
    "brandId": "<brand-uuid>",
    "content": { "body": "Your post text" },
    "targets": [{ "channelId": "<slack-channel-uuid>" }]
  }'

Frequently asked questions

Can an AI agent post to Slack?: Yes. Connect Slack in Mynahcast, give your agent an Agent API key, and it can draft and schedule Slack posts through the MCP server (https://api.mynahcast.xyz/mcp) or the REST API. Each post waits for your approval before it goes out.
How do I post to Slack with an API?: Send POST https://api.mynahcast.xyz/v1/posts with your API key as a bearer token, the brand id, the post body and your Slack channel id as a target. Add an Idempotency-Key header so a retry never posts twice.
What is the character limit for Slack posts in Mynahcast?: Up to 40,000 characters per post. Mynahcast checks the limit before saving, so an agent finds out at validation time, not at publish time.
Is posting to Slack with Mynahcast free?: Every Mynahcast plan includes every live channel, from $12 per month (5 channels) with a 7-day free trial.

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