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

Annotations only declare readOnly and openWorld; the description adds ordering (newest first), source (ESPN public JSON feed), scope (one league, no scores), and crucially payment semantics — $0.002 USDC per successful call via x402 and no charge on failure. That billing detail is genuinely beyond the structured fields; only rate limits/latency are absent.

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?

Front-loaded with the core purpose in the first clause, followed by output shape, ordering, then alternatives and price. The 'Related tools on this server, for a different need:' phrasing is clunky and the pricing sentence is tacked onto the same paragraph, but no sentence is redundant.

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?

Output schema exists, so return-field coverage is bonus rather than necessity, and the description still summarizes it. With a two-param, read-only, paid tool, it covers scope, ordering, source, cost model and alternates — enough for correct invocation; only failure/auth mechanics beyond the pricing line are thin.

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% — both limit (1-25, default 10) and league (with valid values and default) are fully documented in the schema. The prose repeats the league list without adding format or edge-case detail, so 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 verb+resource (latest ESPN news headlines for one league), enumerates the supported leagues, and lists what comes back (headline, description, published time, link). The clause 'ESPN's own feed, no scores' distinguishes it from the many sibling scoreboard tools.

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?

Explicitly frames the alternative use case: point to dev_espn_soccer_scoreboard and dev_espn_college_football when a scoreboard is wanted, and 'no scores' implies news-only routing. It stops short of naming the closest siblings (dev_espn_nba_scoreboard, dev_espn_nfl_scoreboard, etc.), so some inference is still required.

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