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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuine non-annotation context: this is a single-player schedule lookup with a fixed response shape (opponent, home/away, date, points allowed) and a hard scope boundary against comparison or start/sit reasoning.

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 sentences, both earning their place. The response contents are front-loaded and the scope exclusion is packed into the second sentence with no filler.

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 annotations carry the safety profile. The description supplies purpose, scope, and exclusions—everything an agent needs to select and call this single-player lookup correctly.

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 the schema already documents week (1-18), player name format, and the scoring_format enum with its default—so the schema does the heavy lifting. The description's mention of "fantasy points that opponent allowed" loosely ties to scoring_format but adds no syntax or format detail beyond the schema.

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 names a specific resource (a player's weekly opponent) and enumerates what is returned: home/away, game date, and fantasy points allowed to his position. It also names what it is not (compare players, start/sit), which cleanly separates it from siblings like compare_players and get_strength_of_schedule.

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?

It explicitly states the negative scope: "it does not compare players or make a start or sit call," steering the agent away from compare_players and any advice-style tool. It stops short of naming the alternative tool by name, but the exclusion is concrete enough to route correctly.

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