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

Annotations already declare read-only, idempotent, non-destructive behavior, so safety is covered. The description adds real value by disclosing the return contract (true/false plus game page url) and the edge-case behavior of returning false with a reason when the game is not on both platforms. What it does not cover is how the game is matched (exact title vs. fuzzy) or whether a not-found game yields a different response.

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?

Six short sentences, front-loaded with the question it answers, then the return shape, then the constraints, then the sibling alternative. Every sentence carries information an agent needs; nothing is 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 no output schema, the description correctly absorbs the burden of explaining return values, including the failure case. It is nearly complete for a three-parameter query, with the only meaningful gap being the format/expectation for the 'game' argument.

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 and it only partly does: it clarifies the relationship constraint between platform_a and platform_b and defines platform families (PS4/PS5, Xbox One/Series, Switch/Switch 2). It says nothing about what the 'game' string should be (slug, title, id) or how closely the enum labels map to the family names it mentions.

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 question the tool answers ('can players on two different platforms play this game together online?') and what it returns, which distinguishes it from get_game ('For the full matrix of a game use get_game'). An agent can route between the two without opening either schema.

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 gives the intended use case ('quick yes/no'), names the alternative tool and the condition that selects it ('For the full matrix of a game use get_game'), and states a precondition ('platform_a and platform_b must differ'). No when-to-use decision is left to inference.

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