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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the remaining burden is light. The description still adds real value by disclosing the scope of the check — every list Mizan reads plus Steam's own VAC and game bans — which tells the agent what evidence comes back. It omits rate limits or cost of a 100-account call, a minor gap given the output schema covers results.

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?

Two sentences, front-loaded with the batch capability before the detail. The second sentence is long and its final clause ('lines of a server's `status` output work too') largely repeats the schema, but the density is justified by the enumeration of ban sources.

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 an output schema present, the description need not explain return values, and the single input is fully specified. What an agent needs to call it correctly is present; only sibling disambiguation and any scale/cost caveats for 100-account batches are missing.

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 description coverage is 100% and the single parameter already documents SteamID64, STEAM_0:0:11101, [U:1:22202], profile links, and `status` lines. The description restates those accepted formats rather than adding new semantics, so the schema does the heavy lifting and baseline 3 applies.

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?

States a concrete verb and resource ('Check up to 100 Steam accounts in one call') and explains exactly what is retrieved: bans across every list Mizan reads, cheating flags, and Steam's VAC/game bans. The batch framing ('up to 100 ... in one call') implicitly distinguishes it from the single-account lookup_player sibling, but no sibling is named explicitly.

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?

Offers a use case ('such as everyone on a game server') that implies when to reach for batch checking rather than a single lookup. However, it never states when NOT to use it and never names lookup_player as the alternative for one-off checks, so the routing decision is left to inference.

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