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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, open-world), so the description's added value is the paywall behavior: a key is required, and there are two acquisition routes including a free one. That is exactly the kind of gating context an agent cannot infer from structured fields. It stops short of noting rate limits or what the pay-per-call path costs.

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 gating requirement is front-loaded in a bracketed banner, then purpose, then cohort resolution, then the advisory disclaimer. Dense but every sentence carries information. The 'not investment advice' clause is arguably boilerplate, but it is short.

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?

An output schema exists, so the metric list is redundant but harmless and return values need no further explanation. Auth path, cohort sourcing, and scope (single coin vs all coins) are all covered, leaving little an agent would need to guess.

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%, so the baseline would be 3. The description earns above baseline by disclosing the cohort fallback to the HL_WHALE_ADDRESSES environment variable, a default source the schema never mentions. dex, coin and topN are left entirely to 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 — aggregated positioning of a whale cohort for a coin or all coins — and enumerates the exact metrics returned (long/short size & notional, wallet counts, weighted-average entry, net bias, 1h/24h change). An agent can tell this is a cohort-aggregate view rather than a per-wallet view, though no sibling (e.g. hl_smart_money_score, hl_trader_report) is named to sharpen the boundary.

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?

Gives real prerequisites — a premium key, with hl_request_free_key or x402 pay-per-call as the paths — and explains how the cohort is resolved (cohort arg or HL_WHALE_ADDRESSES). It never says when to reach for this instead of hl_smart_money_score or hl_trader_report, so the usage guidance is implied rather than explicit.

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