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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is covered. The description adds real behavioral context by defining the 'heavy' (2+ TE) and 'light' (0-1 TE) buckets and clarifying the two-part current-season/prior-season structure, but it says nothing about scope limits, row counts, or how the limit/plan caps interact.

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 dense, front-loaded sentences with essentially no filler; the 'Two parts' framing immediately orients the reader. The telegraphic, verb-less style is slightly awkward but every clause carries information.

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?

For a tool with no output schema, the description does describe the content of both result sections reasonably well. However, with moderate complexity and a sibling invoke_nfl_personnel_epa, it omits invocation context and sibling differentiation, leaving the agent adequate but not complete information.

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 team, limit, and position are already fully documented in the schema; baseline 3 applies. The description adds no additional parameter meaning (e.g., how position filters the personnel splits), so it neither compensates nor detracts.

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 specifies the returned data in detail (heavy-personnel rate, play action/motion/RPO rates, receiver usage in light vs heavy) but never states an action verb, so the agent must infer that this tool retrieves NFL personnel splits. The content is specific enough to distinguish it from invoke_nfl_personnel_epa, but the purpose is expressed as a data inventory rather than a clear statement of what the tool does.

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?

There is no when-to-use guidance, no mention of when this is preferable to invoke_nfl_personnel_epa or invoke_nfl_coverage_splits, and no indication of prerequisites. The agent gets no routing signal at all.

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