Slack — can an agent use it?
Slack shipped an official MCP server (GA 17/02/2026) and courts agent builders, but its May 2025 terms cut conversations.history to 1 request per minute for commercially distributed non-Marketplace apps and ban using Slack data to train an LLM.
Can an agent get correct information?
Machine-readable surface — 8.5/10
docs.slack.dev serves an open robots.txt that explicitly advertises LLM-friendly markdown ('append .md to any page URL'), and every API response is JSON with structured Block Kit payloads. source
Information retrieval quality — 7/10
Plan prices are public and exact (Free $0 with 90-day history and 10 apps, Pro $7.25/user/mo annual, Business+ $15) but Enterprise+ is 'contact sales' and the MCP server's plan eligibility is published nowhere in Slack's own docs or help centre. source
Documentation for machines — 8.5/10
Per-method reference with required scopes and rate-limit tier, a dated changelog tagged 'Breaking change'/'Deprecation' plus quarterly recaps, and first-party Bolt SDKs — offset by the official OpenAPI spec repo slackapi/slack-api-specs being archived since 27/03/2024. source
Can an agent do the job?
Action coverage — 8.5/10
The Web API covers messaging, channels, files, users, canvases and admin, and 2026 added chat.startStream/appendStream/stopStream plus blocks.validate — but there is no test mode mirroring production and Discovery API export is Enterprise+ only. source
Agent protocol support — 9/10
Official, actively extended MCP server at mcp.slack.com/mcp, GA 17/02/2026 with OAuth 2.1 + PKCE scoped user tokens and new tools shipped Apr–Jun 2026; loses points because it rejects Dynamic Client Registration, so Claude Code and Cursor's default flows fail. source
Access & auth friction — 5.5/10
App creation and tokens are self-serve in minutes with granular scopes, but MCP needs a per-app 'Model Context Protocol' toggle, a user token (xoxp-), workspace-admin approval of the MCP server domain, and any commercial distribution requires Slack Marketplace review with no published turnaround time. source
Agent payment capability — 2/10
Slack sells seat subscriptions but supports no agent payment protocol (no ACP, AP2, MPP or x402) and exposes no purchase or billing-mutation API — team.billing.info is read-only, so money moves only through human checkout or a sales contract. source
Cost & rate fairness — 4.5/10
Standard tiers are documented and generous (Tier 3 = 50+/min, Tier 4 = 100+/min) but non-Marketplace commercially distributed apps created after 29/05/2025 get conversations.history and conversations.replies at 1 request per minute and 15 objects per request — a targeted throttle on third-party data access, with internal apps exempted after the 03/06/2025 clarification. source
Will it still work next quarter?
Permission & ToS stance — 5.5/10
The API ToS effective 10/10/2025 states 'You may not use API Data to train a large language model' for externally offered apps, bans bulk export of messages and files outside the Discovery API, limits storage to what is 'essential for the immediate operation', and makes the Marketplace the only lawful commercial distribution channel — even though bots themselves are first-class citizens. source
Reliability & continuity — 6.5/10
There is a machine-readable status API (slack-status.com/api/v2.0.0/current returns status and active_incidents JSON) and deprecations get long runways (files.upload slipped from 11/03/2025 to 12/11/2025), but the API is not date-versioned, the 29/05/2025 rate-limit cut hit with almost no notice, and a global severe-latency outage on 27/05/2026 was reported by users before the status page updated. source
Sources
Point-in-time assessment — services change terms, prices and APIs often. That volatility is itself scored under Reliability & continuity. Re-verified at least quarterly.
- slack.com/terms-of-service/api — Official Slack API Terms of Service, effective 10/10/2025 — LLM-training ban, bulk-export ban, temporary-storage-only clause, Marketplace-only commercial distribution (accessed 2026-07-25)
- docs.slack.dev/changelog/2025/05/29/rate-limit-chan… — Official changelog: conversations.history and conversations.replies cut to 1 req/min and 15 objects for new non-Marketplace commercially distributed apps (accessed 2026-07-25)
- docs.slack.dev/changelog/2025/06/03/rate-limits-cla… — Official follow-up clarifying that internal customer-built apps keep their existing rate limits (accessed 2026-07-25)
- docs.slack.dev/changelog/2026/02/17/slack-mcp — Official changelog announcing GA of the Slack MCP server and the Real-time Search API, plus the split of search:read into search:read.public/private/im/mpim scopes (accessed 2026-07-25)
- slack.com/blog/news/mcp-real-time-search-api-now-av… — Slack newsroom post, 17/02/2026 — MCP server and RTS API GA after limited release since October 2025; 50+ partners including Anthropic, Google, OpenAI, Perplexity (accessed 2026-07-25)
- slack.com/blog/news/slackbot-mcp-security — Slack post, 17/06/2026 — mcp:connect scope, App Directory review plus admin approval of MCP server domains, off-by-default, per-action confirmation for write/delete tools (accessed 2026-07-25)
- docs.slack.dev/apis/web-api/real-time-search-api — Official RTS API guide — requires xoxp- user token and search:read.public; available to directory-published and internal apps only, not unlisted distributed apps (accessed 2026-07-25)
- docs.slack.dev/apis/web-api/rate-limits — Official rate-limit tiers: Tier 1 1+/min, Tier 2 20+/min, Tier 3 50+/min, Tier 4 100+/min, per method per workspace per app (accessed 2026-07-25)
- slack.com/pricing — 2026 pricing — Free (90-day history, 10 apps), Pro $7.25/user/mo annual, Business+ $15 with Admin analytics API, Enterprise+ contact sales with Discovery API (accessed 2026-07-25)
- docs.slack.dev/changelog/tags/breaking-change — Breaking-change history: files.upload deprecation moved to 12/11/2025; 17/06/2026 system notifications move from Slackbot to USLACK (accessed 2026-07-25)
- slack.dev/slack-developer-changelog-recap-april-jun… — Q2 2026 recap — streaming chat methods, blocks.validate, new MCP server tools, Slackbot MCP client with four auth methods (accessed 2026-07-25)
- adamjones.me/blog/slack-mcp-custom-client — Third-party walkthrough confirming mcp.slack.com/mcp endpoint, PKCE OAuth with xoxp- user tokens, and the required per-app Model Context Protocol toggle (accessed 2026-07-25)
- github.com/anthropics/claude-code/issues/30855 — Reported failure of Slack MCP OAuth in Claude Code — Slack does not support Dynamic Client Registration (accessed 2026-07-25)
- github.com/slackapi/slack-api-specs — Slack's official OpenAPI spec repository, archived read-only since 27/03/2024 (accessed 2026-07-25)
- gvwire.com/2026/05/27/slack-goes-down-for-thousands… — 27/05/2026 global severe-latency outage; 6,000+ Downdetector reports before the status page reflected it (accessed 2026-07-25)
- computerworld.com/article/4005509/salesforce-change… — Third-party reporting on Salesforce restricting bulk Slack data access for LLMs (accessed 2026-07-25)