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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds no behavioral context of its own (no pagination behavior, no note that older seasons may be returned), though the schema's own field notes partially carry that load. No contradiction with annotations.

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 action and resource, followed by the filter set and the discovery pointer. No filler, though the second clause is a dense run-on list rather than cleanly separated guidance.

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 not be described, and the description covers scope, filter dimensions, and the mlb_discovery dependency. It is nearly complete for a read-only leaderboard endpoint; the only gap is explicit disambiguation from the closely named sibling 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 description coverage is 100%, so the schema already documents all nine parameters in detail (including the avg_spin pre-2015 quirk and browser-side team filtering). The description's list of filters (season, pitch threshold, hand, team, sort, pagination) merely restates them and adds no format or syntax detail beyond the schema.

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 states a specific verb ('Fetch') and resource (Baseball Savant's Pitch Arsenals leaderboard) and scopes the metric to speed, percentage, or spin by pitch class. It hints at a distinction via 'separate ... leaderboard' but never names the sibling tool (mlb_statcast_pitch_arsenal) it is meant to contrast with, so sibling differentiation is only implied.

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 one concrete routing instruction ('use mlb_discovery for exact values'), which helps with the team/season inputs, and enumerates the filterable dimensions. However, it never says when to choose this tool over mlb_statcast_pitch_arsenal or mlb_statcast_pitch_arsenal_details, so selection guidance is incomplete.

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