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

Adds real context beyond the readOnly/openWorld annotations: the x-api-key requirement (Pro key or 3-day trial), the Bybit source being conditional on reachability, and the 30-day hard limit. It does not contradict the annotations. Missing only return shape or rate-limit behavior, but the auth/fallback disclosure is above average.

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 what the tool returns, with prerequisites second. Dense but every clause adds useful information; the parenthetical source list is slightly crowded but earns its place.

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?

For a two-parameter, read-only tool with no output schema, the description covers sources, timeframe bounds, auth requirement, and output metric (average APR). The remaining gap is the format of the required 'coin' argument and the shape of returned data, which keeps it from a 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 coverage is 50%: 'days' is documented in the schema as 1-30 default 7, and the description's 'last N days (max 30)' only echoes that. The required 'coin' parameter has no schema description and the description gives no format hint (ticker symbol vs pair), so it does not fully compensate for the gap. 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 specific verb and resource ('Hourly funding history for a coin'), names the venues (Hyperliquid, Bybit) and adds the APR output. It implicitly differs from get_funding_rates (current rates) and find_funding_arbitrage, but never explicitly distinguishes itself from those siblings, 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 by the word 'history' and the 30-day cap; there is no explicit 'use this instead of get_funding_rates when…' guidance and no exclusions. The auth prerequisite is stated, which is the main contextual hint, but routing between siblings is left to inference.

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