does_save_game_exist

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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is fully covered. The description's 'Read-only' line merely restates the annotation, and it adds little else behaviorally (no failure modes or cost). The underlying-function mention and return shape are the only real additions, so a 3 is appropriate.

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 purpose, then alternatives, then return shape — a sensible order with no filler. Slight redundancy: 'returns exists' in prose overlaps with the explicit 'Returns: { ...exists... }' block, and 'Read-only' repeats the annotation.

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 two-parameter existence check with no output schema, the description supplies the return shape, the engine binding, and sibling routing. Nothing an agent needs to call it 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%, so both slot_name and user_index are already documented with meaning (including the desktop default-0 note). The description adds no parameter detail beyond the schema, so the baseline 3 is correct.

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?

States a specific verb (check) and resource (whether a save slot has data), and even names the underlying engine API. An agent can distinguish it from the info-listing siblings without opening a 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?

Explicitly routes the agent: use get_save_game_slot_info for path/size/mtime, or list_save_games to enumerate every slot. This names the alternatives and the conditions that select them, leaving nothing to inference.

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