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

Annotations already declare readOnlyHint, idempotentHint, non-destructive behavior, and closed-world operation. The description adds useful output-cardinality context by saying it suggests ONE item based on mood, time, and players, but it does not explain return format, selection logic, or determinism beyond the annotation.

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 tightly written sentences with no filler. The core action and usage condition are front-loaded and easy to parse.

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 read-only recommendation tool with five optional, fully schema-documented parameters, the description provides enough context to invoke it correctly. It states the input basis and that exactly one suggestion is returned, though it does not detail the result shape.

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%, and each parameter is well documented in the schema, including collection options and all_ages suitability. The description mentions mood, time, and players, but adds no parameter meaning beyond the schema and omits all_ages and collection.

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 names a specific action (suggests), resource (ONE Plot Speaks story or game), and timing/context (to play now). It implies a recommendation role rather than listing, opening, or starting, but does not explicitly name sibling alternatives to distinguish itself.

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?

It gives a clear when-to-use condition: "Use it when they aren't sure what to play." It does not state when not to use it or name alternatives such as list_stories or choose.

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