List Slack Channels

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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering safety. The description adds valuable context: the return format (list of channels with id, name, topic, purpose, member count) and pagination behavior via cursor. It also clarifies the filtering capability. This exceeds the baseline given the strong annotations.

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 well-structured: a clear opening sentence, a formatted Args section, and a Returns line. While the Args section duplicates some schema information, it doesn't feel bloated. It front-loads the purpose and keeps parameter details in a readable list. Minor redundancy with the schema prevents a top score.

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?

For a simple list tool with no output schema, the description is nearly complete. It explains what is returned, covers all parameters, and notes the 'access' scope. It doesn't mention edge cases like partial results (though openWorldHint may cover this), but the core behavior is well explained. Slightly more context on pagination would elevate it.

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 coverage is 100%, so the baseline is 3. The description enhances the schema by enumerating valid values for 'types' (public_channel, private_channel, mpim, im) and clarifying the 'cursor' param as 'from a previous response'. These details add meaningful semantics beyond the schema descriptions.

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 uses a specific verb ('List') and resource ('Slack channels') with a clear scope ('you have access to'). It distinguishes itself from sibling tools like slack_search_messages and slack_get_channel_history by focusing on channel enumeration, and it mentions a filtering option (channels you've joined). This is unambiguous and differentiates from alternatives.

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 clear context for when to use this tool (listing accessible channels) and notes a specific filter (only joined channels). However, it does not explicitly mention when not to use it or name alternative tools, so it stops short of a 5. The usage is clear enough from the description and sibling list.

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