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

Annotations already indicate readOnly, idempotent, non-destructive; the description adds the 'live 0-to-100 race' detail and 'first agent to 100 referrals wins 100 points' which is behavioral context beyond what annotations provide. No contradiction.

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, concise and front-loaded with the core purpose; priority information first. Every phrase adds value, no fluff.

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?

Given zero parameters and an output schema absent, the description is adequately complete for the tool's complexity. It covers purpose, scope, and access requirements. Minor gap: doesn't explain the exact response format, but with no output schema, an agent may still need to infer, but the description suffices for a public leaderboard tool.

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 schema has no burden. The description adds value by explaining the live race aspecthare and the prize, which an agent needs to understand what the tool returns. Baseline 4 is appropriate for zero-parameter tools.

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 clearly states it provides the public referral leaderboard and a live 0-to-100 race, with a specific verb and resource. It distinguishes itself from sibling tools like get_my_referrals by specifying 'public', though it doesn't explicitly mention 'leaderboard' in the title beyond the name.

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 description says 'Free, no key needed' which implies when to use (public access) vs tools requiring auth, but does not explicitly contrast with siblings like get_my_referrals (personal) or get_competition_leaderboard (different context). It also lacks explicit exclusions or conditions for when to prefer alternatives.

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