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

With no annotations and no output schema, the description carries the full behavioral burden and does not meet it. It never states that this is a read-only lookup, what the counts are keyed by, whether they are point-in-time or aggregated, or how 'per-capability' maps to the response.

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?

It is short, but brevity here is under-specification rather than density: two clauses of unexplained jargon instead of a front-loaded purpose. Every word should earn its place, and 'per-capability' and 'non-displayed' do not communicate anything an agent can act on.

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 tool with no annotations, no parameters and no output schema, the description should define the operation and the return shape. Seven opaque words do not tell an agent enough to call the tool correctly or interpret its result.

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 has zero parameters, so there is nothing for the description to explain and the baseline applies. The description does not misstate anything about 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 phrase 'resting order counts' names the resource, but there is no verb (read/lookup) and 'per-capability' and 'non-displayed' are opaque jargon. Nothing distinguishes it from expired, fills, own_orders or posttrade, so an agent cannot confidently select it from siblings.

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 'only (non-displayed)' qualifier implies a narrow scope, but there is no when-to-use or when-not-to-use guidance, and no mention of the alternatives among sibling tools. An agent is left to infer why it would pick book_view over own_orders or fills.

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