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

Annotations already declare it safe/idempotent, and the description adds a lot they cannot: responses come from internal caches, every source is labelled with an as_of, a stale source returns 503 and is explicitly never billed, and each call costs 0.01 USDC via x402 across five chains. That payment/staleness/error behaviour is exactly the disclosure an agent needs before calling a metered tool.

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?

Purpose and ranking are front-loaded, and the staleness/payment facts at the end are load-bearing. The middle is heavy though: four flag definitions with full threshold formulas read like output-schema documentation and make the block dense.

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 metered, read-only, multi-metric board, the description covers scope, defaults, ranking, cache/staleness failure mode, billing, and what per-coin fields exist. With an output schema present it does not need to explain return values, so nothing essential is missing.

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 both parameters are already documented, and the description only restates the same facts ('30 coins by default, up to 60, or the coins you list'). It adds no tie-breaking or interaction rules beyond the schema, so the baseline 3 applies.

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?

It opens with a specific verb and resource ('Signal board for trading bots: the Hyperliquid perp market in one table') and states the ranking key (open interest in USD), so the agent knows exactly what comes back. It never names a sibling (get_perp, get_coin_signal, get_positioning, get_squeeze_score) to differentiate itself, though 'one call is the whole market structure' implies it is the aggregated alternative to the per-metric endpoints.

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?

The description gives operational cadence ('Poll every 1-5 minutes') and scope ('or the coins you list'), which is real usage guidance. But it never says when to reach for this instead of the many sibling market tools, nor any precondition or exclusion — selection is left implicit.

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