perp_funding

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

With no annotations, the description carries the full burden and does so well: it discloses cost ($0.0025 USDC per call), p99 latency (3000ms), zero-required-parameter defaults, and per-venue error handling for unreachable or unlisted coins. Auth/payment mechanics are not explained, 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?

The paragraph is front-loaded with the core purpose, then output fields, then params/cost/latency. It is dense but every clause is load-bearing given the absence of an output schema; the output-field enumeration is long but necessary rather than padded.

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 and no annotations, the description fully specifies the return payload per venue (funding rate, interval hours, APR, mark price, OI USD, next funding time) plus aggregates and error reporting, and adds cost and latency. An agent has everything needed to invoke and interpret it.

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 only 50% (the venues enum has no description), so the description compensates: it states both parameters, gives their defaults (coins=BTC,ETH,SOL; venues=all) and restates the 10-coin cap. These defaults are genuinely additive beyond the schema, though no format or per-venue notes are given.

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 a specific resource (perpetual futures funding rates) with clear scope: up to 10 coins across Binance, Bybit, OKX and Hyperliquid in a single call. An agent can tell this apart from crypto_prices or defi_yields from the content, but the description never explicitly names or contrasts with any sibling, so it stops 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 arbitrage spread hint suggests a use case and the defaults (BTC, ETH, SOL / all venues) make zero-arg invocation possible, but there is no explicit when-to-use, when-not-to-use, or alternative-tool guidance relative to the many sibling market-data tools.

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