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jtalk22

Slack MCP Server

by jtalk22
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JavaScript
Hybrid

slack_conversations_history

Read-onlyIdempotent

Fetch messages from a Slack channel or DM, optionally by time range and limit, and resolve user IDs to display names for readable conversation history.

Instructions

Get messages from a channel or DM with user names resolved

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
limitNoMessages to fetch (max 100, default 50)
latestNoUnix timestamp - get messages before this time (boundary timestamp included)
oldestNoUnix timestamp - get messages after this time (boundary timestamp included)
channel_idYesChannel or DM ID (e.g., D063M4403MW)
provenanceNoAuthor labelling for returned messages. label (default) stamps origin and author_trusted on every message; strict also holds slack_send_message after outside-authored text has been read. Defaults to SLACK_MCP_PROVENANCE, else label. This argument can only tighten labelling, never loosen it: to drop the labels entirely and get the pre-5.1 output shape, set SLACK_MCP_PROVENANCE=off on the server.
resolve_usersNoConvert user IDs to names (default true)
include_all_metadataNoPass Slack's include_all_metadata option to conversations.history
include_rich_message_fieldsNoInclude Slack message attachments, blocks, metadata, files, and reactions when present

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changedv5.1.0
    • addedInput schema / properties / provenance
      Added value: +{
+  "description": "Author labelling for returned messages. label (default) stamps origin and author_trusted on every message; strict also holds slack_send_message after outside-authored text has been read. Defaults to SLACK_MCP_PROVENANCE, else label. This argument can only tighten labelling, never loosen it: to drop the labels entirely and get the pre-5.1 output shape, set SLACK_MCP_PROVENANCE=off on the server.",
+  "enum": [
+    "off",
+    "label",
+    "strict"
+  ],
+  "type": "string"
+}
  2. First observedv4.4.0

TDQS

C2.9/5.0
Behavior2/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, idempotentHint=true and openWorldHint=true, so the safety profile is covered. The description adds only the name-resolution trait, which is already exposed via the resolve_users parameter; it says nothing about pagination, rate limits, or the provenance/labelling behaviour that dominates the schema.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

A single front-loaded sentence with no filler or redundancy. It is efficient, though arguably too terse for an eight-parameter read tool with a non-trivial security-related mode.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema and eight parameters, the description should carry more: how history is windowed/paginated, default ordering, and the behavioural consequence of the provenance modes. None of that appears, so an agent must reverse-engineer usage from the schema alone.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and every parameter (limit, oldest, latest, provenance, resolve_users, include_all_metadata, include_rich_message_fields) carries its own description, so the schema does the heavy lifting. The description adds no timestamp format, pagination, or provenance guidance beyond what is already there, making the baseline 3 correct.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a specific verb and resource (get messages) and bounds the scope to a channel or DM, plus a distinguishing post-processing trait (user names resolved). It does not, however, differentiate itself from near-neighbours like slack_get_full_conversation, slack_get_thread, slack_conversations_unreads, or slack_search_messages.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

There is no statement of when to use this over slack_get_full_conversation, slack_get_thread, or slack_search_messages, and no exclusions or prerequisites. The only routing signal an agent gets is implicit in the phrase 'channel or DM'.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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