opponents_play

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

With no annotations, the description must carry the transparency burden. It discloses two significant behaviors: 'Defaults come from config so the pool matches the user's actual games' and 'Cached locally; a repeated query makes no network call.' It does not explicitly state read-only behavior, but that is clearly implied. It could mention auth or rate limits, but for this simple query tool, the transparency 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?

The description is appropriately concise and front-loaded. The first sentence states the core purpose; the second explains the source variants. The second paragraph adds useful config/caching details without redundancy. No word is 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?

For a simple query tool with 2 parameters and an output schema, the description covers purpose, sources, defaults, and caching behavior. It does not explicitly compare to sibling tools or mention limitations/errors, but it is reasonably complete given the tool's simplicity and the presence of an output schema.

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 0%, so the description must compensate. It fully explains the source parameter (lichess default vs masters) and the config-driven defaults. For fen, it only says 'from a position', which is minimal but somewhat informative. No FEN notation or examples are provided, so the description only partially compensates for the schema's lack of documentation.

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 clearly states the tool's function: 'What gets played from a position' and immediately distinguishes between two sources (lichess vs masters). This is a specific verb+resource+scope that differentiates it from sibling tools like my_results_from_position, which presumably focuses on the user's own results.

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 provides clear context on when to use the tool: to see what opponents play at the user's rating/speed or from masters. It explains the default source and config-based filtering, implying the intended use case. However, it does not explicitly name alternative tools or state when not to use this tool, which prevents a 5.

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