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

Annotations already cover read-only, idempotent, non-destructive, and closed-world behavior. The description adds the important cost signal ('Costs 5 credits'), which is valuable behavioral context not present in the annotations. It does not describe output format, but an output schema exists.

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 description is a single, front-loaded sentence that packs the tool's purpose, supported scopes, and cost without any filler. Every element earns its place.

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 annotations covering safety traits, a 100% schema description coverage, and an output schema handling return values, the description provides all the additional context an agent needs: what the tool returns, the three invocation modes, and the credit cost.

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. The description adds meaningful semantics by mapping the three usage modes to parameter combinations: one game (game_id), one player using PFR id (player_id), or a team's season (team + season). This clarifies how to combine the optional parameters beyond their individual schema descriptions.

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 resource (snap counts) and elaborates on the metrics (offensive, defensive, special-teams snaps and snap shares) and scope (game, player, team season). It clearly distinguishes itself from generic stats tools like get_player_stats, though it does not explicitly name a sibling alternative.

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 phrase 'Use for playing time' gives a clear context for when to use the tool, and the three supported modes (game, player, team season) further guide invocation. It lacks explicit when-not-to-use conditions or named alternatives, which keeps it from a 5.

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