Order-flow toxicity (VPIN) for BTC, ETH, SOL perps

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

Annotations already declare readOnlyHint and openWorldHint, but the description adds meaningful behavioral context: the VPIN scale (0=balanced, 1=fully one-sided), the 90-day percentile, the danger threshold, and the 24h average. It also notes that elevated readings historically precede volatility and warns that VPIN says nothing about direction, which goes beyond the annotation cues.

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 two sentences, front-loaded with the 'Call this when' instruction, followed by a concise explanation of return values and interpretation. Every sentence earns its place with no fluff.

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 fully carries the burden of explaining return values and their meaning. It specifies the current VPIN, percentile, threshold, and 24h average, and provides interpretative guidance. The tool is simple (no params) and the description covers all necessary context.

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 the baseline is 4. The description adds no parameter-specific details (there are none); it is adequate given the empty schema.

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 states the tool's purpose: detecting informed or toxic order flow via VPIN for BTC, ETH, and SOL perps. It uses specific verbs ('Call this when...') and distinguishes itself from sibling tools by focusing on VPIN and order-flow toxicity.

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 explicitly tells when to use the tool ('when the user asks whether informed or toxic order flow is building, about VPIN, or whether market makers are under pressure'). It doesn't name alternatives or state when NOT to use it, but the trigger context is very clear, and the 'VPIN says nothing about direction' caveat subtly hints at scope limits.

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