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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered; the description adds that it takes no arguments and that results are sorted by tier, plus what fields are populated. It does not discuss freshness of the snapshot or rate limits, which would matter for a live OpenDota-sourced dataset, but the additions are meaningful beyond the annotations.

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 return content before the routing guidance, and every clause carries information (fields, sorting, no args, alternative tool). No 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?

An output schema exists, so the field enumeration is partially redundant, but it usefully flags the cumulative/share percent fields an agent would need to answer percentile questions. Combined with the no-argument statement and the sibling routing, an agent has everything required to invoke it correctly.

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?

There are zero parameters, so the baseline is 4, and the description reinforces this by explicitly stating 'Takes no arguments', which removes any doubt about hidden filters. Nothing further can be added.

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 distribution of OpenDota-rated Dota 2 players over rank tiers') and enumerates the fields returned, so the agent knows exactly what this produces. It also names the sibling it is not (opendota_benchmarks), making it distinguishable 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?

Gives explicit usage framing ('Use it to answer what percentile a rank is or how rare Immortal is') and names the alternative tool with the condition that selects it ('use opendota_benchmarks for per-hero performance percentiles'). Both when-to-use and when-to-use-something-else are present.

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