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

Annotations already provide readOnlyHint, idempotentHint, and destructiveHint false. The description adds behavioral context by specifying the ownership and delegation filter, which is beyond the annotations. It clarifies the scope of results without repeating the safety profile.

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 a single, front-loaded sentence with no filler. It states the action and scope immediately, making it easy to parse and efficient.

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 list tool, the description is complete. It explains what is returned (usernames owned by wallet, filtered by delegation) and the annotations cover safety. No output schema exists, but the purpose is simple enough that a detailed return format is not necessary.

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, and the schema is empty (100% coverage). Per the rubric, a baseline of 4 is appropriate when there are no parameters to document. The description does not need to add parameter semantics since none exist.

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 action (List), the resource (.t.me Telegram Usernames), and the scope (owned by the authorized wallet, filtered by domain delegation). This precisely distinguishes it from sibling tools like domains.list (which lists domains) and domains.records (which lists DNS records).

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 on what is listed (usernames owned by the wallet, filtered by delegation), but does not explicitly mention alternatives or when not to use this tool. It is clear enough that an agent can infer when to use it, but it lacks explicit exclusions or named alternatives.

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