Metadata for several games at once

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

Beyond the readOnlyHint and openWorldHint annotations, the description discloses critical behavioral traits: 'COSTS ONE REQUEST PER GAME' and 'Results are cached for six hours.' This adds cost and caching context not captured in annotations, which is essential for an agent deciding whether to call this tool repeatedly.

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?

Each of the four sentences earns its place: purpose, cost warning, usage guidance, and caching behavior. The information is front-loaded and directly actionable, with no filler or repetition. It is concise yet comprehensive.

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?

Given the absence of an output schema, the description still covers the returned metadata fields (platforms, genres, year, rating, playtime), the cost model, caching behavior, and explicit guidance on when to use this tool versus query_library. This is complete context for an agent to select and invoke the tool effectively.

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 documents 'games' as 'Up to 25 names, slugs or ids' but leaves include_playtime with only a default. The description mentions 'playtime' in the metadata list, hinting at the parameter's role, but does not explicitly explain that include_playtime toggles playtime output. With 50% schema coverage, the description partially compensates but leaves a gap in 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 opens with a clear verb-resource pairing: 'Platforms, genres, year, rating and playtime for a set of games.' It explicitly scopes the tool to sets of games and lists the metadata fields. It also distinguishes itself from sibling tools like query_library and get_game by contrasting library queries with custom lists, making its purpose unambiguous.

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 provides explicit guidance: 'prefer query_library when the set is really a library query' and 'Use this for sets that are not a library query — most often the contents of a custom list.' It even gives an example ('which of my VR list are on Quest 3'), clearly stating when to use this tool versus alternatives.

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