Slack Web API Skill

Use this skill to run Slack Web API operations through uxc + OpenAPI.

Reuse the uxc skill for shared execution, auth, and error-handling guidance.

Prerequisites

• - uxc is installed and available in PATH.
• Network access to https://slack.com/api.
• Access to the curated OpenAPI schema URL:

• - A Slack bot token and, for selected thread/history reads, an optional user token.

Scope

This skill covers a Messaging Core surface:

• - auth validation
• channel lookup and inspection
• conversation history reads
• thread replies reads
• posting messages, including replies via INLINECODE6
• adding reactions

This skill does not cover:

• - Slack OAuth app installation flow
• file upload flows
• INLINECODE7, admin.*, or usergroups.* method families

Subscribe / Socket Mode Status

Slack inbound events can be delivered through Socket Mode. uxc now has a built-in Slack Socket Mode transport, but this skill still treats it as a limited event-ingest path rather than a fully packaged workflow surface.

Current uxc subscribe status:

• - Slack Web API request/response calls are supported by this skill
• a live Socket Mode smoke test succeeded with the built-in transport:

• - a real inbound message event was validated end-to-end:

What the current built-in transport already handles:

• - app-level xapp-... auth via INLINECODE17
• automatic apps.connections.open before each connect attempt
• raw Socket Mode frame capture
• automatic ack for envelopes that carry INLINECODE19

What is still not packaged:

• - event-shape guidance per subscribed Slack event family
• higher-level workflow packaging for common Slack event intake flows

Slack Socket Mode is now a validated IM subscribe provider at the transport/runtime level.

Authentication

Slack Web API uses Authorization: Bearer <token>.

Token types used in practice:

• - xoxb-...: Bot User OAuth Token. This is the recommended default for this skill.
• INLINECODE22: User OAuth Token. Use this only when you explicitly want user-token semantics.
• INLINECODE23: App-level token. Use this for Socket Mode subscribe, not for normal Web API methods.

To create an app-level xapp-... token for Socket Mode:

1. 1. Open the target Slack app at INLINECODE25
2. Go to INLINECODE26
3. Find INLINECODE27
4. Generate a token with the connections:write scope
5. Enable Socket Mode in the app configuration before relying on subscribe-based event intake

Option 1: Bot Token (Recommended Default)

Use the Slack Bot User OAuth Token (xoxb-...) for the default binding and for most messaging operations:

CODEBLOCK0

Option 2: User Token (Explicit Override For Selected Reads)

Use a separate Slack User OAuth Token (xoxp-...) when the method requires user-token semantics, especially thread/history access outside bot-accessible conversations:

CODEBLOCK1

Do not bind slack-user by default to the same host/path. Invoke it explicitly when needed:

CODEBLOCK2

If you intentionally want writes to appear as the installing user rather than the bot, you can also invoke write methods with --auth slack-user, but treat that as an explicit override rather than the default path.

Core Workflow

1. 1. Use the fixed link command by default:

1. 2. Inspect operation schema first:

1. 3. Prefer read validation before writes:

1. 4. Execute with key/value or positional JSON:

Operation Groups

Read / Lookup

• - INLINECODE47
• INLINECODE48
• INLINECODE49
• INLINECODE50
• INLINECODE51

Messaging / Reactions

• - INLINECODE52
• INLINECODE53

Guardrails

• - Keep automation on the JSON output envelope; do not use --text.
• Parse stable fields first: ok, kind, protocol, data, error.
• Bot token is the recommended default for send and basic read flows.
• Bot token means Slack Bot User OAuth Token (xoxb-...); do not confuse it with xapp-... app-level tokens.
• User token means Slack User OAuth Token (xoxp-...); use --auth slack-user when you intentionally need user identity or user-token-only reads.
• INLINECODE66 has token-type restrictions:

• - get:/conversations.history only returns conversations visible to the supplied token; a bot token is limited to joined conversations.
• Slack rate limits for conversations.history and conversations.replies vary by app distribution. Slack documents a tighter limit for newly created commercially distributed non-Marketplace apps starting on May 29, 2025; do not assume generic Tier 3 behavior.
• Treat post:/chat.postMessage and post:/reactions.add as write/high-risk operations; require explicit user confirmation before execution.
• INLINECODE73 is equivalent to uxc https://slack.com/api --schema-url <slack_openapi_schema> <operation> ....

References

• - Usage patterns: INLINECODE75
• Curated OpenAPI schema: INLINECODE76
• Slack Web API docs: https://docs.slack.dev/apis/web-api
• INLINECODE77: https://docs.slack.dev/reference/methods/chat.postMessage
• INLINECODE78: https://docs.slack.dev/reference/methods/conversations.history
• INLINECODE79: https://docs.slack.dev/reference/methods/conversations.replies/