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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so safety is covered. The description adds the credit cost ('Costs 5 credits'), which is real behavioral information the annotations do not carry. It does not disclose pagination behavior, though the output schema and limit param partly cover that.

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: the capability and supported query shapes come first, the cost note follows. No filler, nothing repeated from the name or title.

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 no explanation, and the description covers all three access patterns for a 6-parameter, zero-required tool. It does not clarify how parameters combine (e.g., whether season is mandatory alongside team/player) or what happens with no filters, which is a modest remaining gap.

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 six parameters, including that player_id is a PFR id sourced from search_players. The description's mention of game/player/team-season modes maps to game_id, player_id, and team but adds no syntax or format detail beyond the schema. 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-and-resource purpose ('playing time: offensive, defensive, and special-teams snaps and snap shares') and enumerates the three query shapes (game, player by PFR id, team season). No sibling tool covers snap counts, and the description makes that scope explicit.

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?

'Use for playing time' plus the three supported query modes gives clear context for when to reach for this tool rather than get_player_stats or get_team_stats. It stops short of naming an explicit alternative or stating exclusions, so it is clear but not fully routing.

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