Slack MCP Server

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

No annotations are provided, so the description carries full burden. It states it's a read operation ('Get'), but doesn't disclose behavioral traits like permissions required, rate limits, pagination, error conditions, or what specific data the 'Dictionary' contains. The description is minimal beyond the basic purpose.

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: the first sentence states the purpose clearly, followed by structured Args and Returns sections. Every sentence earns its place without redundancy or fluff.

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 moderate complexity (2 required parameters, read-only operation) and the presence of an output schema (which handles return values), the description is reasonably complete. It covers purpose and parameters, but lacks behavioral context like error handling or permissions, which would be beneficial since annotations are absent.

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 0%, so the description must compensate. It adds meaning by explaining that 'channel_id' identifies the channel containing the message and 'timestamp' identifies the message itself, including an example for channel_id. This clarifies the semantics beyond the bare schema, though it doesn't specify the timestamp format.

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 specific action ('Get all reactions') on a specific resource ('on a specific message'). It distinguishes itself from siblings like 'get_channel_history' or 'get_thread_replies' by focusing exclusively on reactions rather than message content or thread context.

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 implies usage when reactions on a specific message are needed, but provides no explicit guidance on when to use this tool versus alternatives like 'get_channel_history' (which might include reactions) or 'remove_reaction' (for deletion). No exclusions or prerequisites are mentioned.

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