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

Annotations already mark the tool as read-only and not open-world, and the description adds useful behavioral detail: invite-only, key-protected, and encrypted-only channels are never listed, and no authentication is required. This goes beyond the annotations and helps the agent understand the filtering and access semantics.

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?

Three short sentences with no wasted words. The main action is front-loaded, followed by usage guidance, exclusions, and auth requirement. Each sentence adds value.

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 zero-parameter read-only tool with an output schema, the description is complete. It explains what is returned, when to use it, what is excluded, and that authentication is not required. No important information is missing for an agent to invoke it correctly.

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 tool has zero parameters, so parameter documentation is not needed. The description still covers the output focus with 'member counts and topics', and the schema is fully covered by the absence of parameters.

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 states a specific verb and resource: 'List the public channels on this server' with member counts and topics. It also clarifies scope by explicitly excluding non-public channels, which distinguishes it from the sibling tools that deal with history, pins, search, and verification.

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 phrase 'Start here when you do not know a channel's exact name' gives clear guidance on when to use this tool. It implies this tool is the entry point before using search or other channel-specific tools, though it does not explicitly name alternatives or describe when not to use it.

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