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

Annotations already cover read-only and open-world, so the description adds real value beyond them: the upstream source (ESPN public stats API, with a note that Baseball-Reference blocks automated access), the non-obvious ascending sort direction for ERA and WHIP, and the x402 payment model ($0.002 USDC per successful call, failures uncharged). The pricing and non-charging-on-failure disclosure is exactly the kind of behavioral context annotations cannot express.

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?

The content is front-loaded — scope, stat groups, filters, then data source, alternatives, and price. The long parenthetical stat enumeration is dense but earns its place by telling the agent what columns come back; the only mild waste is naming two clearly different-sport siblings whose relevance is self-evident.

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 the description needn't explain return shape, and it covers default sort, sort direction, time range, season-type switches, source, and cost. What's left implicit is pagination mechanics (page 1-40 against limit 1-50) and whether qualifiedOnly meaningfully truncates the leaderboard, both of which an agent would want before paging.

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 the baseline is 3, but the description adds semantics the schema lacks: the default sort is home runs, and ERA/WHIP sort lowest-first rather than descending. These are ordering behaviors that materially change result interpretation and are not stated in the sort parameter's enumeration.

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 opens with a precise verb+resource+scope: MLB player season statistics delivered as a sorted leaderboard, defaulting to home runs, with the full stat set enumerated. It explicitly separates itself from same-server siblings (dev_pro_football_reference for NFL, dev_hockey_reference for NHL) and implicitly from other MLB tools via the ESPN data-source note.

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?

It gives clear usage context (regular season or postseason, 2002 to now, leaderboard-style ranking) and names two alternatives with the condition that selects them. It does not distinguish itself from the other MLB stat siblings in the server (dev_mlb_stats, dev_mlb_statsapi, dev_espn_mlb_scoreboard), which is the notable gap for a crowded sport vertical.

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