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 that filtering is 'with the supplied filters' and enumerates the row types, but discloses nothing beyond that about data freshness, rate limits, or server-side vs local filtering (the local behavior lives only in the schema).

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 tight sentences, front-loaded with the action and resource, followed immediately by sibling routing. No filler and nothing 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?

With an output schema handling return values and annotations covering the safety profile, the description only needs to establish purpose and routing, which it does completely. All 14 params are optional and fully documented, so no gaps remain.

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% and each parameter is already documented, so the schema carries the burden. The description adds no syntax or default details beyond what the schema provides, making the baseline 3 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?

Specific verb (Fetch) plus precise resource (Baseball Savant Arm Value leaderboard rows) and explicit scope (runners, fielders, pitchers, teams, league totals). It also names the arm-value variants it is not, letting an agent distinguish it from mlb_statcast_arm_value_details without opening either schema.

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?

The description routes to three alternatives with reasons: details for game-level plays, fielding_run_value for fielding metrics, discovery for filter values. It provides clear selection context but stops short of stating when this tool is the correct pick over near-neighbors like arm_strength or run_value.

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