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

With no annotations present, the description carries the full burden and does meaningful work: it discloses partial-failure behavior ('Venues that fail are listed under errors'), billing semantics ('the call fails (and is not charged) only if none answers'), and the exact cost ($0.005 USDC per call). It omits auth requirements, rate limits, and latency expectations, which keeps it from a 5.

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 dense sentences, with the resource and venue scope front-loaded and cost/error semantics placed last where they matter least. The field enumeration is long but each item is a distinct returned metric, so it earns its space; a slightly tighter grouping of the funding metrics would improve it.

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?

No output schema exists, so the description must describe return values — and it does so thoroughly, including per-venue fields, a summary block (total OI/volume, weighted funding, mark-price dispersion), and partial-failure handling. For a single-parameter read tool this covers everything an agent needs to call it and interpret results.

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% so the baseline is 3, but the description adds genuinely new meaning by listing accepted symbol formats ('BTC, BTCUSDT, BTC/USDT or XBT') that the schema's single example does not cover. That directly reduces malformed-input risk for the one required parameter.

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 specific resource (one asset's perpetual futures across OKX, Hyperliquid, dYdX and Kraken Futures) and enumerates the metrics returned, so an agent can tell it apart from generic price tools like crypto_price or pair_data. It does not explicitly name the nearest overlapping siblings (funding_rate_arbitrage, open_interest_change), so it falls short of a 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?

Usage is only implied: the agent must infer that this is the tool to call when it needs a cross-venue perp snapshot for a single asset. There is no explicit when-to-use statement, no exclusion of alternative tools, and no prerequisites such as authentication or symbol support limits.

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