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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive, so the description's 'Read-only' is confirmation rather than new insight. It does add genuinely new behavior: ambiguous or unknown names return an error with up to 5 retry suggestions, and it discloses the breadth of the response payload. Return formatting and pagination are not relevant here since it is a single-record lookup.

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?

Front-loaded with the trigger, then the payload, then the exception case, then the sibling routing. The payload enumeration is dense but each item is a distinct capability an agent would want to know. Slightly overlong as a single sentence, but 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?

There is no output schema, so the description takes responsibility for describing the return shape and does so explicitly. It also covers the main failure mode (ambiguous name) and how to recover. Nothing an agent needs to invoke this correctly is missing.

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% and the single parameter is already documented as 'Game name or slug' with an example. The description's 'Accepts the game name or slug' restates that, though the error/suggestion behavior hints at how fuzzy matching works without specifying tolerances. Baseline 3 is appropriate when the schema carries the parameter burden.

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 opens with a concrete trigger and enumerates exactly what the tool returns: platforms, player counts, pairwise crossplay, session length, single-copy sufficiency, and a CoopGames link. This is clearly distinguishable from search_games (discovery) and crossplay_check (single pairwise answer).

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 states the when ('user names a specific game and wants the full multiplayer picture') and names the alternative with its selection condition ('For a single yes/no between two platforms, crossplay_check is lighter'). No ambiguity about which sibling to pick.

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