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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds meaningful context beyond them: the data is live ('right now'), which explains idempotentHint=false, and it notes output parity with the game's Discord bot, setting expectations about content and presentation.

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 tight sentences, with the default no-argument behavior front-loaded before the name-based variant. The closing Discord-bot comparison earns its place as a mental model, though it is the least essential sentence.

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?

With no output schema, the description carries the burden of describing returns and does so by enumerating the data fields for both modes. It stops short of describing response structure or formatting, but an agent has enough to call it correctly and anticipate what comes back.

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 100%, so both parameters are already documented, setting a baseline of 3. The description goes further by explaining what supplying `name` actually changes in the response (race, clan, clan rank, remorts, online status), which is behavioral meaning the schema does not convey. `lang` is left entirely to the schema.

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 names the exact resource (characters online, Discord bridge users, weekly peak/uniques) and clearly describes the second mode triggered by a name. An agent can distinguish this from every sibling (help_*, item_search, news_*) without opening any schema.

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?

It states the branching condition explicitly: omit the name for a live roster, supply a name for a single character's race, clan, clan rank and remorts regardless of online status. There are no competing alternatives among siblings, so the lack of an explicit 'when not to use' is a minor gap.

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