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

With no annotations, the description carries the full behavioral burden. It does usefully disclose the paid-call model ($0.005 USDC per call via x402 on Base) and per-venue data-availability caveats (24h change only Binance/Bybit, long/short ratio only Binance), but says nothing about behavior for unknown symbols, missing venues, or empty results.

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?

A single dense sentence that front-loads the payload and appends pricing last. Every clause carries information, though the enumeration of return fields is long enough that it could be split for scannability.

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 well by listing the return fields and their venue-dependent availability. For a one-parameter lookup tool, the main remaining gap is error/empty-result behavior and whether all four venues always appear.

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?

Only one parameter exists and schema description coverage is 100%, so the schema already explains that 'symbol' is a coin ticker. The description reinforces that the symbol identifies a coin whose perpetuals are measured across venues, but adds no syntax or format detail beyond the schema's example.

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 exact resource (open interest of a coin's perpetual, broken out per venue) and enumerates the returned payload: contracts and USD, market share, 24h change, Binance long/short ratio. That is clearly distinct from siblings like perps_funding or perps_extremes, though no sibling is named explicitly.

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 statement of when to choose this over perps_funding, perps_extremes, or depth tools, and no prerequisites are given. The only conditional information is coverage ('24h change where history exists'), which describes output rather than when to invoke.

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