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

Annotations already cover safety (readOnlyHint, idempotentHint, openWorldHint, non-destructive). The description adds meaningful behavioral details: cost per call ($0.001 USDC), ordering (oldest first), and the bounding 'to the window each interval can carry'. These go beyond annotation defaults without contradicting them.

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?

Two sentences, front-loaded with the core return data and ordering. The cost and API equivalence notes are relevant and concise. No redundant phrasing or filler.

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 an output schema present, return details are covered by structure. The description adds cost, ordering, and window-bounding—enough for an agent to correctly invoke and interpret results. No missing prerequisites or error conditions are critical for a read-only, idempotent tool of this simplicity.

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 100% with descriptions for coin, limit, and interval. The description adds some nuance ('bounded to the window each interval can carry') that clarifies how limit interacts with interval, but it largely relies on the schema for parameter meanings. This meets the baseline for well-documented parameters.

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 states a specific verb ('candleSnapshot for one Hyperliquid perp') and lists the exact fields returned (open, high, low, close, volume, order count) plus ordering ('oldest first'). It clearly distinguishes this from other exchange candle tools by naming Hyperliquid, and the byte-identical reference to a specific REST endpoint leaves no ambiguity.

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 clearly indicates this is for Hyperliquid perpetuals, giving context for when to use it among many market_* siblings. It does not explicitly name alternative tools or state when not to use it, but the 'for one Hyperliquid perp' phrase provides enough context to route an agent correctly.

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