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

Annotations already declare readOnlyHint and openWorldHint, so the description's contribution is the payment model: $0.002 USDC per successful call via x402 on Base/Solana/Arc, failures not charged. It also discloses provenance (ESPN public stats API, PFR blocking automation), which explains data freshness/coverage. Missing rate limits or pagination ceiling, so not 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?

Three tight sentences: what it returns first, then coverage window, then source and price. No filler, and the highest-value information (resource identity) is front-loaded.

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, return values need no explanation, and the description covers data source, temporal scope, season type, and cost — enough to call it confidently. Only pagination/volume expectations and any latency caveat 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?

Schema coverage is 100%, so every parameter already has a description with defaults and ranges. The description only adds the default sort value (passing yards) and the season floor of 2004, both marginal over the schema — baseline 3 is appropriate.

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 concrete verb+resource: an NFL player season statistics leaderboard, and enumerates the stat families returned (passing, rushing, receiving, defense, scoring, returns, kicking, punting). This clearly separates it from scoreboard siblings like dev_espn_nfl_scoreboard and from aggregate tools like dev_nfl_stats.

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 scope cues — regular season or playoffs, 2004 to now, default sort of passing yards — but never says when to choose this over the many sibling NFL/ESPN tools, nor any prerequisite for the paid call beyond the price line. Usage is implied by scope rather than stated.

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