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

Annotations only say readOnly and openWorld; the description adds material operational facts beyond them — an UNISAT_API_KEY is required, the upstream source is the UniSat Open API, and the call costs $0.002 USDC via x402 with failures not charged. Cost and credential requirements are exactly the kind of behavior an agent needs before invoking.

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 output contents are front-loaded in the first clause, followed by requirement, alternatives, and pricing in a logical order. It is dense but slightly redundant in re-stating the 1-144 range already present in 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 a simple one-parameter read tool with an output schema and annotations, everything an agent needs is present: what it returns, auth requirement, cost model, and which siblings to prefer for adjacent needs. No material gap remains.

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?

With schema description coverage at 100% and a single documented parameter, the schema already carries the meaning. The description merely restates the range and default (1-144, default 6) rather than adding interpretation, 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?

States a specific verb+resource — Bitcoin Ordinals inscription activity over the last N blocks — and enumerates exactly what the result contains (total events, per-block/per-hour breakdowns, latest event sample). The UniSat Open API provenance and the named sibling comparisons make it clearly distinguishable from other Bitcoin-block tools.

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?

Explicitly routes the agent away from two siblings with qualifying conditions: use crypto_btc_blocks_range for up to 144 consecutive blocks, and crypto_btc_chain_tips for stale/orphaned blocks and forks. It lacks an explicit statement of when Ordinals activity is the right signal (e.g. vs. general block data), so it falls just short of full when/when-not coverage.

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