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

Annotations already declare readOnlyHint=true and openWorldHint=true, lowering the burden. The description adds genuinely useful behavior beyond that: rows are sorted and paginated *locally*, and league averages are returned alongside rows. It stops short of noting rate limits or response shape, but with annotations covering the safety profile this is solid.

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?

Purpose is front-loaded in the first sentence and the second sentence efficiently covers the filter surface, local sorting/pagination, and the mlb_discovery pointer. The filter enumeration is dense but each item maps to real parameters, so few words are wasted.

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 15 params fully documented, an output schema present, and annotations carrying the safety/open-world profile, the description supplies what remains needed: what is fetched (rows plus league averages) and that sorting/pagination are local. Nothing critical for correct invocation is missing.

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 15 parameters with defaults, ranges, and documented values. The description only re-enumerates the filter dimensions (seasons, team, pitch types, handedness, dates, grouping) without adding syntax or meaning beyond the schema, 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 ("Fetch") and a precise resource ("Baseball Savant Pitcher Arm Angle rows and league averages"), which distinguishes it from sibling statcast tools like mlb_statcast_arm_strength and mlb_statcast_arm_value. It does not, however, explicitly contrast itself against the generic mlb_statcast tool, so the differentiation is implicit in the resource name rather than stated.

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 gives one concrete routing hint — "Use mlb_discovery for exact values" — which tells the agent where to source valid ids/codes. However, it never says when to choose this tool over other statcast or generic Statcast tools, so alternate-selection guidance is absent.

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