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

readOnlyHint=true already tells the agent this is a safe read operation. The description adds that all data is aggregated into one response, which is useful context, but it does not disclose latency, error behavior for unknown symbols, or whether data is live or cached. With annotations covering the safety profile, a moderate added-value score is appropriate.

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 opening sentence is long but front-loads the tool's value and enumerates only substantive data points; the second sentence covers input flexibility. There is no filler, though the list could be slightly trimmed for readability.

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 the description need not specify return shape, and all three parameters are fully documented in the schema. For a complex aggregate read, the remaining gap is usage routing against siblings, which keeps it at 4 rather than 5.

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%, so the schema already documents symbol, exchange, and lang with examples and enums. The description restates the symbol flexibility (BTCUSDT vs BTC) but adds no syntax or constraint beyond what the schema provides. Baseline 3 is correct when the schema does the heavy lifting.

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 the resource ('one perpetual pair') and enumerates the exact data returned (funding rate, settlement timing, mark price, OI, orderbook walls, cross-exchange view), making the tool's scope unambiguous. It implies comprehensiveness ('Everything the radar knows... in a single answer') but never explicitly contrasts itself with focused siblings like funding_history or settlement_calendar, so a 4 rather than 5.

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?

There is no explicit when-to-use or when-not-to-use guidance. The phrase 'in a single answer' implies this is the comprehensive alternative to narrower tools, but the agent must infer that routing. No exclusions or prerequisites are stated.

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