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

Annotations already mark this as read-only, idempotent, and non-destructive, covering the safety profile. The description adds useful context: the handle becomes a subdomain and the character rules (3-63 chars, lowercase, hyphens). It doesn't detail the return format, but for a check operation this is a minor omission given 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 two concise sentences, front-loaded with the primary action and followed by relevant constraints. No wasted words.

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 one-parameter tool, the description covers usage timing, validation rules, and the subdomain format. The absence of an output schema for a check tool means the return value (e.g., boolean) is not explicitly stated, which is a slight gap but not critical given the simplicity.

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 schema fully describes the single parameter with an example. The tool description adds extra semantics by explaining the subdomain format and charset constraints, which are not present in the schema, thus enriching parameter understanding.

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 'Check' and clearly identifies the resource as 'channel handle availability'. It distinguishes itself from sibling tools like create_channel by focusing on the pre-check action.

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 'before trying to create it' provides clear context that this should be used prior to create_channel. It doesn't explicitly name alternatives or exclusions, but the usage timing is obvious from the context.

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