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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description goes further by enumerating the exact returned fields, giving a full example response payload, and noting the interpretive rule (rising OI + high funding = overcrowded), which is context the annotations cannot convey. It stops short of stating data freshness/latency or failure modes.

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-loads the purpose, then usage, then returns — good ordering. The embedded example response JSON is long, but it is justified because there is no output schema and it communicates the return shape more precisely than a field list alone. Slightly heavy overall but every section 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?

With no output schema, the description compensates by listing returned fields and showing a full example response, and it supplies routing guidance against 21 siblings. An agent has everything needed to select and call this tool correctly; only latency/caching behavior is unstated, which is minor.

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 there is a single optional 'asset' parameter with a default, so the schema carries the burden; the description only echoes 'for any asset'. Baseline 3 is appropriate since the description adds no format, valid-set, or defaulting semantics beyond the schema.

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 (total open interest in perpetual futures) plus the key derived metrics (1h/24h change), and explicitly names the sibling tools it complements (funding_rates) and is not (pre_trade_check). An agent can distinguish it from market_snapshot, funding_rates, and pre_trade_check without opening any 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?

Provides an explicit 'Use when' with a concrete condition (need total OI and its direction) and an explicit 'Not for' routing two adjacent needs — funding cost — to funding_rates and trade verdicts to pre_trade_check. This is the full when/when-not/alternatives pattern.

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