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

With no annotations available, the description carries the burden of explaining behavior. It usefully discloses the fee calculation details, the minimum and cap amounts, per-lease-per-day charging, and pricing at event-time rate. However, it never explicitly states whether this is a read-only retrieval, what operations are performed, or what the response shape looks like.

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 compact and front-loaded, starting with the core purpose and then providing the fee detail and the useful distinction from fee_bps. No words are wasted, though the long parenthetical fee explanation makes the first sentence somewhat dense.

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 gives a solid overview of what the ledger reports and how fees are computed, which is useful for a two-parameter read-style tool. However, it omits parameter semantics, an explicit when-to-use statement, and any indication of response structure or operational limits, leaving clear gaps given the absence of annotations and 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 description coverage is 0%, and the description says nothing about account_token or days. The agent receives no additional meaning about how the usage ledger is scoped, how far back the data reaches, or the role of the required account_token. The mention of 'per UTC day' is only weakly related to the days parameter and does not explain it.

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 clearly identifies account_usage as a metered usage ledger and enumerates its contents: placements, destroys, estimated hours, USD, and platform fee. It names the tool's focus unambiguously, though it does not explicitly differentiate itself from a sibling tool by name or contrast with an alternative.

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 provides no guidance on when to use account_usage versus a sibling tool such as true_cost_notes or idle_history. The only distinction is a contrast with fee_bps, which appears to be a field or separate concept, not a tool alternative, so the agent is left without usage conditions or exclusions.

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