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 tool retrieves presence information but doesn't describe traits like rate limits, authentication needs, error handling, or whether it's a read-only operation. While 'Get' implies a read, it lacks details on permissions or potential side effects, leaving gaps for a tool with no annotation coverage.

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 appropriately sized and front-loaded, with the core purpose stated first. The Args and Returns sections are structured clearly, though they could be more concise. Every sentence adds value, but the formatting with separate sections is slightly verbose for such a simple tool.

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 tool's low complexity (1 parameter, no nested objects) and the presence of an output schema, the description is somewhat complete. It covers the basic purpose and parameter, but with no annotations and minimal behavioral details, it falls short of being fully informative. The output schema handles return values, but the description lacks context on usage or limitations.

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?

The description adds minimal semantics beyond the input schema. It explains 'user_id' as 'The ID of the user (e.g., "U01234567")', providing an example that clarifies the expected format, which is useful since schema description coverage is 0%. However, with only one parameter, the baseline is 4, but the description doesn't fully compensate for the lack of schema details, such as constraints or validation rules.

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 tool's purpose: 'Get the presence/online status of a user.' It specifies the verb ('Get') and resource ('presence/online status of a user'), making the function unambiguous. However, it doesn't explicitly differentiate from sibling tools like 'get_user_info' or 'get_user_profile', which might also provide user-related data.

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. It doesn't mention sibling tools such as 'get_user_info' or 'get_user_profile', nor does it specify prerequisites or contexts for usage. The only implied usage is to retrieve presence status, but no explicit when/when-not instructions are given.

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