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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, and the description adds genuinely new operational context: a 60-second data freshness window and a hard batching ceiling of 5 symbols per call. It also instructs the agent to quote the plain-language per-symbol notes, which is behavioral guidance the annotations cannot supply. It does not detail auth or rate-limit behavior, keeping it just below the top.

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?

Front-loaded with the resource and scope, then the differentiating question-set. Dense but every clause earns its place; only the closing 'up to 5 symbols per call' is redundant with the schema.

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?

An output schema exists, so return values needn't be spelled out, yet the description still explains the OI×price regime taxonomy and the top-trader/taker-flow breakdown, which materially helps interpretation. Combined with the freshness and batching facts, an agent has everything needed to call it correctly; the only mild gap is unstated alternatives.

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 100%, and the schema already documents the symbols array (max 5) and the bare-base-asset fallback ('BTC' → USDT perpetual). The description's 'up to 5 symbols per call' merely restates maxItems, adding no new syntax or format meaning, so the baseline 3 applies.

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?

States a precise verb and resource — funding rate, open interest, and positioning for Binance USDⓈ-M perpetual futures — and explicitly carves out its territory against a named sibling ('the derivatives questions candles cannot answer'), so an agent can route between get_derivatives and get_candles without reading either schema.

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 framing 'the derivatives questions candles cannot answer' plus the enumerated use cases (is funding high, is OI building or unwinding, which way accounts lean) tells the agent when this tool is the right pick. It stops short of naming the other alternatives (get_market_stats, get_technical_indicators) or stating exclusions, so it is clear context rather than explicit when/when-not routing.

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