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 and the description's real contribution is the ordering guarantee (most-played first) and the per-row match count. It does not address the implied non-idempotency (idempotentHint=false) or note that counts change as new matches are processed, nor how truncation at 'limit' manifests.

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?

One front-loaded sentence carries the resource, the ordering, and the returned metric, with the optional filter appended rather than buried. No redundant restatement of the tool name or empty filler.

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 2-parameter read-only ranking tool with no output schema and annotations covering safety, the definition covers purpose, ordering, output content, and the optional filter. Minor gaps remain around pagination/truncation behavior and whether the ranking window is all-time or otherwise scoped.

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 the baseline would be 3, but the description adds genuine meaning by naming list_versions as the source of version_id and by stating the filter restricts the ranking itself ('Only rank characters played in this game version'). The limit parameter 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?

States a specific verb and resource ('List the characters'), plus the ranking semantics ('most matches, most-played first') and what each row contains ('the number of matches each appeared in'). That framing separates it cleanly from lookup-style siblings like find_character and from list_archetypes, which ranks a different entity.

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?

Gives clear context for the optional filter, including how to obtain the value: 'version_id from list_versions'. It does not state when NOT to use this tool (e.g. use find_character for a single known character), so it stops short of full when/when-not guidance.

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