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

With no annotations provided, the description carries the disclosure burden and does well: it reveals the return payload fields, the recording cadence, the provenance (FortFi records hourly because Hyperliquid keeps none), and a hard data-start constraint of 2026-11-05 that materially affects requests. Gaps remain around response shape (array vs object), behavior when hours exceeds recorded history, and any per-symbol coverage caveats.

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, zero filler, with the data payload described first and the critical availability caveat second. No sentence could be removed without losing information an agent needs.

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 tool with full schema documentation and no output schema, the description covers what is returned, the units, the derived deltas, granularity, and the history window. It stops short of describing how the response is structured or how truncation near 2026-11-05 is handled, which are the remaining unknowns for a caller.

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, and the description adds genuine domain meaning on top by clarifying that the symbol may be a core perp or a HIP-3 builder perp — a non-obvious expansion of the schema's bare 'e.g. BTC or xyz:CL'. It also implies the hours parameter is measured in hours at hourly granularity, though it does not restate the 1-2160 range or the default.

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 precise resource and payload: hourly open interest for a single Hyperliquid perp, in both coins and dollars, with price and funding per hour and 1h/24h/7d deltas. That is far more specific than the sibling data tools (get_hyperliquid_history, get_hyperliquid_market, get_hyperliquid_cross_section), though it never explicitly names which sibling to use for adjacent needs, keeping it 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 implied rather than stated: an agent infers this tool is for OI history, and the note that FortFi only records from 2026-11-05 functions as a de facto 'when not to use' boundary. There is no explicit guidance on alternatives for shorter-interval or non-OI data, and no mention of what happens for symbols lacking coverage.

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