slack-mcp

refresh_user_cache

Clear the cached user directory to resolve outdated handles or failed user lookups. Returns the number of cached entries cleared.

Instructions

Clear the user cache. Use this when user handles are outdated or if user lookups are failing. Returns the number of cached entries cleared.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "refresh_user_cache"
  }
}

Input Schema

Name	Required	Description	Default
No arguments

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Aug 30, 2026

TDQS

A4.5/5.0

Behavior4/5

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

The description discloses the mutation ('Clear the user cache') and adds a behavioral detail beyond the annotations: it 'Returns the number of cached entries cleared.' It does not contradict the readOnlyHint=false annotation, and it provides useful context about the operation's effect despite destructiveHint=false.

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

Conciseness5/5

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

Two short sentences, each earning its place: the first states the action, the second provides both usage context and the return value. There is no filler, redundancy, or unnecessary technical speculation.

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

Completeness5/5

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

For a zero-parameter cache-clearing tool with an output schema already present, the description is fully sufficient. It explains what the tool does, when to use it, and what it returns, leaving no meaningful gap for an agent to call it correctly.

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

Parameters4/5

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

The tool has zero parameters, so the description does not need to explain parameter behavior. Baseline for zero-parameter tools is 4, and the description correctly adds no irrelevant parameter information.

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

Purpose5/5

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

The description uses a specific verb ('clear') and resource ('user cache'), and explicitly differentiates from the sibling refresh_channel_cache by naming the cache type. Even with the generic title, the first sentence gives an agent a clear, unambiguous action.

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

Usage Guidelines4/5

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

The description gives an explicit trigger: 'Use this when user handles are outdated or if user lookups are failing.' This is clear contextual guidance, though it does not state exclusions or name an alternative tool for resolving lookups, so it falls just short of full when-not/alternatives coverage.

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