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

The readOnlyHint annotation already establishes this is a safe, non-mutating read, so the description needn't restate safety. It does add useful content beyond annotations by indicating the payload includes currency, owned shapes, and the full for-sale list with pricing — but it says nothing about ordering, size, or whether the sale list is filtered.

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?

A single sentence, front-loaded with the summary 'All you hold' before enumerating contents; nothing is redundant. It is slightly costly in flavor wording ('shapes') where plain terms like items would be clearer.

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 carries the burden of describing returns, and it lists the three main components (dollars, owned shapes, purchasable shapes with cost). It stops short of indicating response structure or whether the catalog is exhaustive, which matters for a zero-parameter tool whose whole value is the returned data.

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 and the schema is an empty object, so there is no parameter meaning to add; baseline 4 applies. The description appropriately spends no space on inputs.

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 conveys retrieval of the agent's holdings — dollars, owned 'shapes', and the sale catalog with prices — but never uses a clear verb+resource framing; 'shapes' is in-world jargon that only becomes clear by inference from siblings like unlock_shape. Its scope is distinguishable from mutators such as add_object or unlock_shape, but the purpose is stated poetically rather than precisely.

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?

There is no explicit when-to-use guidance, no prerequisites, and no mention of alternatives such as appearance or textures, which might also expose collection-like data. The agent must infer that this is the read tool for checking funds and owned/purchasable items.

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