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

With no annotations provided, the description carries the full burden and discloses meaningful behavioral traits: data is 'computed from chain-timestamped logs' and 'tokens with no settlement in the window are omitted, never zero-filled'. These details go beyond a simple data summary and help set expectations for data completeness and source, which is valuable for a read-only tool.

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 a single dense sentence but every clause contributes specific information about the metrics and behavior. It is not as tightly structured as a two-sentence summary, and the opening phrase 'the layer that exists nowhere else' is slightly promotional, but it avoids redundancy and stays focused on content.

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?

Despite having no output schema, the description covers the key return aspects: what metrics are included (offHoursPct, minted/burned shares, dvpVwapUsd), how they are computed, and the omission policy. It implicitly indicates a per-stock breakdown through 'per-stock settlement activity'. For a tool with a single parameter and relatively clear scope, this is sufficiently complete.

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 input schema provides 100% coverage with a single parameter, `window`, including an enum and a description ('settlement window (default 24h)'). The tool description does not mention the parameter or add any additional nuance beyond what the schema already states, so the baseline of 3 is appropriate.

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 identifies the resource as 'per-stock settlement activity' and enumerates specific metrics (offHoursPct, minted/burned shares, dvpVwapUsd), making the tool's scope clear. However, it lacks an explicit verb like 'retrieves' or 'lists', instead using a noun phrase, which slightly reduces clarity. It does differentiate from siblings by emphasizing 'the layer that exists nowhere else'.

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 when to use this tool by claiming its content 'exists nowhere else', suggesting it is the sole source for these settlement metrics. It does not name alternative tools or provide explicit when-to-use/when-not-to-use guidance, leaving the user to infer usage from the unique data claims.

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