Slack MCP Server

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the action ('List all users') but doesn't mention key behaviors like pagination (implied by the 'cursor' parameter in the schema), rate limits, authentication requirements, or what the output format looks like (e.g., list of user objects). This leaves significant gaps for an agent to understand how to use it effectively.

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

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

The description is a single, efficient sentence that directly states the tool's purpose without unnecessary words. It's front-loaded and easy to parse, earning its place by providing the core functionality.

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

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

Given the complexity of a list operation with pagination and no output schema or annotations, the description is incomplete. It doesn't cover behavioral aspects like pagination mechanics, response format, or error handling. For a tool with 2 parameters and no structured output information, more context is needed to guide an agent fully.

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

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

Schema description coverage is 100%, with clear documentation for 'limit' and 'cursor' parameters. The description doesn't add any semantic details beyond what the schema provides (e.g., it doesn't explain how pagination works or typical use cases for the parameters). Baseline 3 is appropriate since the schema does the heavy lifting.

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

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

The description clearly states the verb ('List') and resource ('all users in the Slack workspace'), making the purpose immediately understandable. However, it doesn't explicitly differentiate from sibling tools like 'slack_get_user_info' or 'slack_get_user_profile', which might retrieve specific user details rather than listing all users.

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

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

The description provides no guidance on when to use this tool versus alternatives. For example, it doesn't mention how this differs from 'slack_get_user_info' (which likely fetches a single user) or 'slack_get_user_profile' (which might retrieve profile details). There's no context on prerequisites, such as workspace access, or exclusions.

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