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

No annotations are provided, so the description carries the full burden. It helpfully discloses the return shape (status, rounds, UTC times, answer-key hash), implying a safe read, but says nothing about auth requirements, rate limits, or whether the list is filtered by user.

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?

The content is front-loaded with the scope ("All 24 leagues") and the category list is parenthetical context. Slightly dense, but every clause conveys useful information about scope, contents, or the optional filter.

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 and no annotations, the description does a decent job describing what is returned, covering the main fields an agent would need. It omits auth/pagination details, but for a single-parameter listing tool this is largely complete.

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%, so the baseline is 3. The description adds meaning beyond the terse schema note by explaining that passing league switches the result to a single league, and it groups the 24 enum values into recognizable categories, aiding selection.

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 states a specific resource (all 24 leagues) and enumerates what is returned: each league's status plus its rounds with open/close times and answer-key hash. This clearly distinguishes it from siblings like arena_leaderboard or arena_info, though it doesn't name those alternatives directly.

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?

"Pass league to get just one" implies how to narrow scope, giving minimal usage guidance. There is no explicit when-to-use-this-vs-another-tool statement and no mention of prerequisites or alternatives like arena_round_tasks.

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