Which of your lists contain a game

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

The description adds behavioral context beyond the annotations: it reports every custom list, indicates a boolean containment check, and reveals the output purpose (list IDs for add_game_to_lists). Annotations already declare readOnlyHint=true and destructiveHint=false, so the description complements rather than contradicts.

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 two concise sentences, front-loaded with the core behavior and followed by a practical output note. Every word earns its place with no redundancy or 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?

With no output schema, the description gives a reasonable overview of what is returned: lists and whether they contain the game, plus the list IDs for downstream use. It is sufficient for a simple read-only tool, though it could explicitly outline the response structure for full completeness.

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 for both parameters is 100%, with the game parameter fully describing accepted formats (title, slug, numeric ID) and only_containing explaining its filter. The description adds no parameter-specific details beyond the overall behavior, so it does not elevate semantics beyond the schema.

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 'Report every one of your custom lists and whether it contains this game,' specifying a distinct verb (report) and resource (custom lists with containment status). It differentiates from sibling tools like get_lists by focusing on game membership, and even ties to add_game_to_lists by returning needed list IDs.

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 clear context for when to use the tool: to check which custom lists contain a specific game. It implicitly distinguishes from alternatives like get_lists (which likely lists all lists without game filtering) and hints at a workflow with add_game_to_lists, though it does not explicitly state when not to use it.

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