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

Annotations already cover readOnly/openWorld, so the description's value-add here is real: it discloses newest-first ordering and, importantly, that the unfiltered payload is roughly 300 KB — a concrete cost signal an agent can use to prefer filtered calls. It does not discuss pagination or per-call rate limits, keeping it short of 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?

Front-loaded with the returned data shape, then filters, then a downstream-use note and a size warning — a logical order with no filler. It is a single dense paragraph, so the size warning and cross-tool routing are slightly buried.

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 does not need to enumerate return fields, yet it still sketches the season/split/tournament nesting, and it documents all four filters plus the practical size constraint. Only the choice among sibling calendar-style tools (lolesports_schedule, lolesports_tournaments) is left implicit.

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 the parameter descriptions already name each filter's provenance (league_id from lolesports_leagues, season_id from an earlier call), so the description largely restates structured data. It does add the region value examples (KOREA, EMEA, NORTH AMERICA, INTERNATIONAL, GLOBAL) and the combined-filter effect, which is a marginal lift over 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 (returns the LoL esports calendar since 2011) and immediately differentiates itself from siblings lolesports_tournaments/lolesports_leagues by explaining the season > split > tournament hierarchy it returns. An agent knows exactly what shape of data to expect 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?

Explains what each optional filter does when to apply it (season_id for one season, region for one region's splits, league_id for one league's tournaments) and routes downstream work to lolesports_standings / lolesports_completed_events via tournament ids. Missing only explicit guidance on when to prefer a different entry-point tool such as lolesports_tournaments.

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