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

With no annotations, the description carries the full burden. It discloses that this is a creation operation and that it returns initial state, but it does not mention side effects, persistence, or error behavior. It gives some useful behavioral context but leaves room for ambiguity about what 'create' implies server-side.

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 concise sentences: the first states the primary purpose and output, the second clarifies variant formatting with examples. Every sentence earns its place with no 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?

The description covers the essential workflow for a create tool: what it does, what it returns, and how variants work. Although there is no output schema, it tells the agent that the return value is initial state for subsequent calls, which is sufficient for an agent to proceed. Minor gaps around state persistence and error handling are not critical given the simplicity and sibling context.

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 baseline is 3. The description adds concrete variant examples ('grand+random', 'standard+drops'), which helps clarify the variant parameter beyond the schema's generic description, but it does not add meaning for family or rngSeed beyond what the schema already provides.

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 uses a specific verb ('Create') and resource ('game instance for a given family'), clearly distinguishing it from sibling tools like play_apply_move and play_check_status. It also states the key output (initial state), so an agent knows what this tool accomplishes.

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 a workflow: create a new game instance first, then pass the returned initial state to subsequent calls. This is clear enough context for when to use it, though it doesn't explicitly name alternatives or 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.