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

Annotations already cover readOnlyHint and openWorldHint, but the description adds genuinely valuable behavioral context: a paid x402 call at $0.002 USDC per successful call, accepted chains (Base, Solana, Arc), and that failed calls are not charged. Return format is not described, but an output schema exists to cover that.

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 core purpose followed by the payment detail. Efficient and every clause is relevant, though the pricing enumeration is slightly lengthy.

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 and full annotation coverage mean the description doesn't need to explain returns or safety. Given a simple 2-param read tool, the only minor gap is the absence of any guidance on sibling selection among many football tools.

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 both parameters (limit, position) are already fully documented with ranges and defaults. The description adds no syntax or constraint detail beyond the schema, so the baseline 3 applies.

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 resource (Fantasy Premier League player stats) with a specific data source (official FPL feed) and enumerates the returned fields (team, position, goals, assists, form, price, ownership %). An agent can easily distinguish this from sibling soccer tools like dev_espn_soccer_scoreboard or dev_fbref.

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?

Implies usage (top players by total points, current season) but never states when to choose this over the many other football/stat siblings, nor any prerequisites or exclusions. Context is implied rather than explicit.

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