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

The annotations already declare read-only and idempotent behavior, but the description adds important context beyond that: keyless returns only the proven-trader cohort, a plan returns every tracked account up to the row cap, since_ms is a polling cursor, and this is 'descriptive market data only'. None of this contradicts the annotations.

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 description is compact and front-loaded with the most important identifying information, followed by concrete usage examples and behavioral caveats. Every sentence earns its place; there is no filler or restatement of the schema.

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?

Given the annotations, the complete 100% schema coverage, and the presence of an output schema, the description covers what an agent needs to select and invoke the tool: the event type, returned fields, filters, polling cursor semantics, and access-tier behavior. There is no obvious missing context that would cause a wrong call.

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, but the description adds useful meaning by summarizing the filter dimensions ('Filter by coin, wallet or kind') and tying since_ms to a polling cursor and next_since_ms. It also gives limit-related context through the plan row-cap behavior, going slightly beyond the raw field descriptions.

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 opens with a clear verb-resource pair: 'What named Hyperliquid accounts just DID', then enumerates the concrete move kinds (open, add, trim, close, flip) and the returned fields (coin, side, size, standing position, leverage, liquidation price). This distinguishes it from sibling tools like hl_traders or hl_wallet, which focus on profiles or balances rather than position-change events.

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?

It gives explicit use examples ('what did the big accounts just do', 'did anyone flip short on BTC', 'what is Trader 7 doing') and explains the keyless vs. plan behavior, which tells an agent when it can get the cohort view versus all tracked accounts. It does not explicitly name sibling alternatives or state when not to use this tool, so it stops short of a 5.

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