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

Annotations already establish that the tool is read-only, non-destructive, and idempotent, so the description does not need to restate those. It adds meaningful behavioral detail by specifying exactly what is returned: per-bucket series, buy/sell ratio, and cumulative volume delta, which goes beyond the annotation metadata.

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 focused sentence with no filler. It front-loads the core metric and venue, then packs the key return values and analytical use case into the closing clause without redundancy.

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 simple read-only tool with four parameters and no output schema, the description covers the essential domain context, the return shape, and the analytical purpose. It could go slightly further by noting default behavior around periods or buckets, but the schema already documents those defaults.

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 coverage is 75%, so most parameters are already documented. The description adds value for the undocumented instId by clarifying that it refers to a crypto perpetual contract on OKX, and it reinforces that period controls the bucketing behavior.

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 names a precise resource and metric — taker buy versus taker sell volume for a crypto perpetual contract on OKX — and immediately differentiates it from generic volume or trade tools by stating it returns the buy/sell ratio and CVD. It clearly identifies the output series, not just an abstract action.

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 gives an implied use case by calling it 'the aggressor-flow input for order-flow and CVD analysis,' so an agent can infer when it is relevant. However, it does not explicitly state when to prefer this over related tools like trades, candles, or perp_metrics, nor does it name any alternatives.

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