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

With no annotations, the description carries the full transparency burden. It discloses the returned data (title, year, publisher, etc.) and 'Fetch' implies read-only, but it does not address failure modes (e.g., not found), authentication, or other behavioral nuances. It provides basic context but lacks depth.

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 a single, tightly packed sentence that covers purpose, parameters, and return fields. No word is wasted, and it is front-loaded with the core action.

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 two-parameter lookup with no output schema, the description is largely complete: it explains what the tool does, how to invoke it, and what it returns. Missing details like error responses or system identifier format are not critical given the simplicity and the presence of sibling tools like list_systems.

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?

The schema already describes slug_or_hash, and the description reiterates that. It adds that the lookup is per system, but leaves the 'system' parameter vague (no format or example). Schema coverage is 50%, so the description partially compensates but doesn't fully clarify all parameter semantics.

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 with a specific verb ('Fetch'), a specific resource ('a single game'), and the exact lookup criteria ('by system + canonical slug OR ROM hash'). It also lists the returned fields, making the purpose unmistakable. This distinguishes it from sibling tools like search_games (search) and list_systems (systems list).

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 implies usage: use when you have both a system and a canonical slug or ROM hash. It does not explicitly mention alternatives or exclusions, such as 'use search_games when you don't have the exact slug.' The context is clear but the guidance is not explicitly articulated.

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