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

Annotations already declare this a safe, idempotent read, so the bar is lower; the description still adds real behavior: results are ordered largest-first, each row reports whether Mizan is still reading the list, and filtering is optional. It does not state pagination behavior beyond the schema's limit default, which keeps it off a 5.

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, zero filler: the purpose and ordering lead, and the optional filters close. The field enumeration on the return side is mildly redundant given an output schema exists, but it is compact and reads naturally as part of the opening claim.

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 low-complexity, zero-required-parameter list tool with annotations and an output schema, this covers what an agent needs: what it returns, ordering, and filter options. The only missing piece is how this relates to registry_stats when the caller does not know a game key.

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% and each parameter already carries its own description, including the game-key pattern and the "part of a name" example. The description only restates that both filters exist without adding format, matching rules, or interaction between them, so the 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?

"List the ban lists Mizan reads, largest first" pairs a specific verb with a specific resource and adds ordering, then enumerates the fields each entry carries (issuer, games, ban counts, tracking status). No sibling tool (check_players, lookup_player, list_my_communities, registry_stats) touches ban lists, so the resource alone distinguishes it.

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 final clause states the two available narrowing options, which implies how to use the tool, but gives no when-to-use vs when-not guidance and never points at registry_stats for enumerating game keys (that pointer lives only in the schema). Adequate, not instructive.

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