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

Annotations already declare readOnlyHint=true, destructiveHint=false, and idempotentHint=false. The description adds important cost and billing behavior ('Price $0.01/call via x402 USDC or a card key (/credits), first 25 free; failed calls free') and emphasizes that repeats are charged, which is not in annotations. It also reiterates the read-only nature, aligning with annotations.

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 front-loaded with the core purpose and then adds use cases, an example, and pricing details. It is mostly efficient, though the pricing and billing sentences could be seen as slightly verbose for a tool selection description, but they are relevant.

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 tool with no output schema, the description covers purpose, use cases, example, cost, and behavior. However, it does not describe the return format (e.g., how teams are presented), which would be helpful given the absence of an output schema.

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 the schema fully documents both parameters. The description provides an example for 'items' that reinforces the comma-separated format, but adds no new semantic constraints or meaning beyond what the schema already states.

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 ('split') and resource ('list of names') and clarifies the outcome ('random, evenly sized teams'). This distinguishes it from sibling tools like random_shuffle or random_pick, which do not divide into teams.

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?

Gives clear use cases ('games, workshops and classrooms') but does not explicitly say when to use this versus alternatives like random_shuffle, or mention prerequisites or exclusions. The context is helpful but not exhaustive.

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