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agents:SKILL.mdmcp.jsonopenapi.yml

← Slack

Can an agent post a message to a channel with Slack Web API?

The agent needs you to sign it up or register a client and provide a key or token. You also handle changes to its access. Interface found; job not yet run.

observedProbed revision sha256:34c32aa3075e…

Who does each step

how grades work →

Whether the agent handles it alone or a person has to step in.

  1. 01

    Discover

    Machine

    The vendor's machine-readable docs show the agent where and how to call this job.

  2. 02

    Access

    Workaround · setup

    You give the agent a key or token.

  3. 03

    Onboard

    Workaround · setup

    You sign up or register a client for the agent.

  4. 04

    Pay

    Not applicable

    Nothing to pay for the job.

  5. 05

    Confirm

    Machine

    The response or specification defines errors the agent can distinguish from success.

  6. 06

    Sustain

    Workaround · setup

    You replace or revoke the agent's access when it needs to change.

  • Access: handing over a key or token.
  • Onboard: signing up or registering a client for the agent.
  • Sustain: renewing, replacing or revoking its access.

To remove these handoffs: support OAuth client registration so the agent can register its own client and ask for consent; provide an agent registration route, such as auth.md, a sign-up API or OAuth client registration; provide key management or OAuth refresh and revocation so the agent can maintain its own access.

Agent surfaces

2 kinds · 4 entries
For agents
slack.com2 more
slack.com/llms.txtmcp.slack.com/llms.txt
Names the job's endpoint
OAuth
mcp.slack.com
authorization server · protected resource

The probe

12 Oct 2026 · 00:13 UTC · 40.37 s

Each request it sent and what came back; the descriptors it read, counted, with what they named.

Discover29 descriptor reads6 facts
Found
For agentsslack.com/llms.txtOAuthmcp.slack.comOAuthmcp.slack.comOAuthmcp.slack.comFor agentsmcp.slack.com/llms.txtFor agentsslack.com
From
slack.com/llms.txt · mcp.slack.com/.well-known/oauth-authorization-server · mcp.slack.com/.well-known/oauth-protected-resource · mcp.slack.com/llms.txt
This endpoint
slack.com/api is named by a document written for agents
Job requestPOST slack.com/api/chat.postMessage20040 ms
Request
POST https://slack.com/api/chat.postMessage
Response
200 · application/json · 114 bytes
Body
sha256:7bd2fcecea4a3cf67657d10d8cb1cc3f287259f3249859c42bddd39d6ddf03dd
Exchange
sha256:42d6771beabf17641877eb0fc03c02895cdfc137834605a0f482489383c0a495
Resource metadataGET slack.com/.well-known/oauth-protected-resource/api/chat.postMessage40440 ms
Request
GET https://slack.com/.well-known/oauth-protected-resource/api/chat.postMessage
Response
404 · text/html · 1736 bytes
Body
sha256:ade10e41702572444c079d4070ae0a376f0d167c7d053cb8d15bca5a3d24b004
Exchange
sha256:e7420c7de4b5a9be5dc3857436a387c329f4ce79dc5ada4ed2d6fa62782829c0
Resource metadataGET slack.com/.well-known/oauth-protected-resource40455 ms
Request
GET https://slack.com/.well-known/oauth-protected-resource
Response
404 · text/html · 45148 bytes
Body
sha256:617647ae88ea7b14540220bb62bf04166c6b9647baea5ea953a133c4c4f73048
Exchange
sha256:077d076ac65dedf815e1faf3109a889e55950dea02f4a6f0b5394649c3770c7d
Job requestsession openedPOST mcp.slack.com/mcp40138 ms
Request
POST https://mcp.slack.com/mcp
Response
401 · application/json · 77 bytes
Body
sha256:f53ac16a775917fe6dd1caf35105662193030ee76ec6227bf140646d3e1bded4
Exchange
sha256:a0ac215e0821d70bc2cf19a08277089e939713ddd42cda9adb2364b7dbdf7abb
Resource metadataGET mcp.slack.com/.well-known/oauth-protected-resource20040 ms
Request
GET https://mcp.slack.com/.well-known/oauth-protected-resource
Response
200 · application/json · 757 bytes
Body
sha256:19ec25f364665494d250e48ff0ac4cc6f5779f05cbc51f26139ca6183909ded7
Exchange
sha256:44fde57e5408e374f7a8a10e4e1dfd7599a2825bc9cc72141b54d5f94421867e
Authorization serverGET mcp.slack.com/.well-known/oauth-authorization-server20040 ms
Request
GET https://mcp.slack.com/.well-known/oauth-authorization-server
Response
200 · application/json · 1008 bytes
Body
sha256:0032884c8d36253d31313163faaa0a7126c6208505f27db762ad7ae5591839d9
Exchange
sha256:a11274cc8a37bb30f60f4e29e880002323b217acd9aa4208b573ca276e77bb64
Declared pageGET slack.com/get-started403125 ms
Request
GET https://slack.com/get-started
Response
403 · text/html · 39826 bytes
Body
sha256:3005952268db99d5b60ea83f85fbd6c0733d56dfd386ffb3457bd068fc555f4f
Exchange
sha256:42d4686763cfcae2d4334bcb0f4817f28096431aa0deb08e5cd89b91b4b414dd

The grade’s badge

One image that keeps itself current, linking here.

Live badge for Slack Web API, agent grade: B+[![agent grade](https://sourcey.com/badges/agent-readiness/arp_01m4pm5cg0ebphc7096n6mvsgs.svg)](https://sourcey.com/c/slack/agent-readiness/slack-web-api/chat-message-post)

Improve the report

Correct it, probe it again, or improve the path.

Report outdated evidenceRequest reassessmentClaim this record
Profile
arp_01m4pm5cg0ebphc7096n6mvsgs
Projection
sha256:9d6a49c2306d8cf0b236f000c688b94ad383108b8098b36278e6275675fe3733
Policy
kind-2026-10-12.2 · sha256:b612172aad277b54461de84e006815126f2df566563954b02f4432a39cad89ac

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