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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=false, so the safety profile is covered. The description adds useful behavioral detail about the returned payload (subscription names, monthly price, leave date only 'when announced'), implying an occasionally-absent field. It omits any auth, rate-limit, or failure-mode context, so it adds moderate rather than rich value on top of annotations.

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, front-loaded with the user-facing questions that establish intent, followed by the concrete return contents. The three example questions are slightly repetitive but each maps to a distinct user need, so no sentence is clearly 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?

No output schema exists, so the description carries the burden of explaining return values, and it does: which subscriptions include the game, their monthly price, and the leave date when announced. Combined with the fully documented input schema, an agent has enough to call and interpret it, though regional price variation or the case where a game is on no subscription is not addressed.

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%: the schema fully documents region (allowed values tr/us/eu/gb, IP-based default) and game_id (Steam AppID or IGDB id format). The description only alludes to region scoping ('include the game in a region') and adds no format or syntax detail beyond the schema, so the 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?

The description states a specific capability: it answers whether a game is on Game Pass, which subscriptions include it, the monthly price, and the leave date. The example questions pin down the resource and intent precisely, so an agent can distinguish it from deal/pricing siblings. It stops short of naming an alternative sibling explicitly, which keeps it at 4 rather than 5.

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 three quoted user questions ('Is <game> on Game Pass?', 'When does <game> leave Game Pass?', 'Can I play <game> with a subscription?') act as concrete triggers for when to call this tool, which is strong context. However, there is no explicit when-not-to-use guidance or routing to siblings like get_offers or get_cheapest_way_to_play when the question is about price/deals rather than subscription eligibility.

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