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

With no annotations, the description carries the full burden and does well: it discloses the play-permission prerequisite, that only active copies are returned, that rows are per-copy not per-quantity, and that gift notes/private messages/attachments are omitted. It omits ordering, pagination, and empty-result behavior.

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 tight sentences, front-loaded with the core action and scope. Every clause adds information an agent would otherwise have to guess (row granularity, permission, exclusions).

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?

There is no output schema or annotation coverage, so the description must explain return values, which it does by naming the fields and row semantics. It leaves out pagination/limits and error behavior, but those are minor for a simple no-parameter listing tool.

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 tool takes zero parameters, so the baseline is 4 and no schema semantics need to be added. The description correctly adds nothing about parameters and instead spends its words on return structure.

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 ("List") and resource ("your account's active invention copies") and enumerates the fields returned. The sentence "Each row is one copy, not a quantity stack" explicitly distinguishes it from stack-based inventory-style siblings such as inventory.

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 context for use: active invention copies belonging to the account, gated by play permission. It does not name an alternative sibling (e.g. blueprint_list, inventory) or state when not to use it, so it falls short of a 5.

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