Check if a username is available

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

Annotations already declare readOnlyHint=true, so the read-only behavior is known. The description adds the channel/supergroup scoping but does not describe behavior for unavailable usernames or potential edge cases. With annotations present, this is adequate but not rich.

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 wasted words. It conveys the essential action and target resource effectively.

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?

Despite the tool's simplicity and read-only annotations, the complete lack of parameter documentation and usage guidance makes it incomplete for an agent. The 'peer' parameter is particularly ambiguous, and no return behavior is specified.

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 0% and no parameter descriptions are provided. The description clarifies that 'username' refers to a channel/supergroup username, but 'peer' and 'accountId' remain unexplained, leaving the agent uncertain about required inputs.

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 tool's function: it verifies whether a desired channel/supergroup username is free. This distinguishes it from siblings like update_username (which modifies) and resolve_username (which resolves existing usernames), making the purpose unambiguous.

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 usage context is implied (pre-checking username availability before claiming one), but there is no explicit guidance on when to use this tool versus alternatives like resolve_username or update_username. No exclusions or alternative recommendations are provided.

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