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

Annotations cover safety (readOnlyHint, openWorldHint), and the description adds information they cannot convey: the data source is the official public API with no key, it is updated by World Rugby, and each successful call costs $0.002 USDC via x402 on Base/Solana/Arc with failures not charged. That payment/auth context is exactly the extra layer annotations cannot express; it stops short of describing freshness cadence or result ordering.

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 resource and its fields, with the pricing/access note last. Dense but every clause is functional; the parenthetical payment-channel list is slightly busy but justifies its space.

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 return values need not be explained. Access model, cost, and data-source caveats are covered; only the update cadence and whether results are strictly ordered by rank are 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?

The single parameter has 100% schema coverage with its own range and default documented, so the schema carries the load. The description adds nothing parameter-specific beyond 'from the current table', making the baseline 3 correct.

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?

Names a specific resource ('World Rugby men's 15s world rankings') and enumerates exactly what it returns (position, team, country code, rating, previous position/points). The 'men's rankings only' and '15s' qualifiers make it trivially distinguishable from sibling ranking tools like search_fifa_team_rankings or search_owgr_golf_rankings.

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?

Usage is implied by the sport-specific scope rather than stated. There is no explicit 'use this when…' guidance, no mention of when to prefer a general web/news search sibling, though the men's-only constraint does function as an implicit exclusion.

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