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

Annotations only declare readOnly and openWorld; the description adds genuinely non-obvious behavior — cost of $0.005 USDC per successful x402 call across Base/Solana/Arc, failure not charged, and the 144-block (roughly one-day) measurement window. It doesn't mention rate limits or staleness/latency of the price feed, keeping it short of a 5.

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?

Metrics are listed first, then the formula, then sibling routing, then pricing — a sensible front-loaded order with no filler. The inline formula is dense and arguably belongs in a docstring, which keeps it from being maximally tight.

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 params and an output schema already defining the return shape, the description covers what remains: data scope, time window, cost, and alternatives. Only minor gaps — no statement of how often the underlying data refreshes or of any failure modes beyond billing.

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?

The tool takes zero parameters, so there is nothing to disambiguate; the baseline applies. The formula given is an explanation of computation, not parameter meaning, and is a small bonus rather than required content.

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 specific outputs — hashprice in USD and sats/TH/s/day, subsidy-vs-fee revenue split over the last 144 blocks, network hashrate/difficulty, and BTC price — so an agent knows exactly what it gets back and can distinguish it from hashrate-only or block-level siblings.

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 explicitly routes an agent away to crypto_btc_mining_pools (pool hashrate / block shares) and crypto_btc_block (per-height detail), which is real alternative guidance. It does not, however, say when this is preferable to crypto_bitcoin_hashrate_difficulty or crypto_kaspa_mining_economics, so exclusions are only partial.

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