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

Goes well past the readOnly/openWorld annotations by disclosing the billing model ($0.003 USDC per successful call, x402 on Base/Solana/Arc) and that failed calls are free — critical cost behavior an agent must know before calling. It also discloses the temporal nature (snapshot vs. live stream) and asset coverage limits, which shape how results should be interpreted.

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?

Effectively three sentences, front-loaded with the core operation before scope limits and pricing. The colon-list of returned fields is dense but not wasteful; no filler or marketing language. Slightly packed, but every clause carries operational meaning.

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 an output schema present, the description needn't explain return values, and it doesn't over-invest there. It still covers the gaps structured fields can't: chain/asset coverage, snapshot semantics, and per-call cost with payment rails. An agent has everything needed to decide and call correctly.

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 all three parameters and their defaults/ranges are already documented. The description adds one genuinely new interpretation — that 5 blocks is 'about one minute of chain time' — plus the 'at least a USD threshold' framing, but otherwise restates what the schema already says. Baseline 3 with a small lift.

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 precise verb+resource+scope: large ETH/USDT/USDC transfers in the latest 1-10 Ethereum blocks above a USD threshold, with the exact fields returned. Explicitly bounds scope ('Ethereum only; other tokens are not included') and distinguishes itself from a streaming tool ('a snapshot, not a live stream'). It does not name which sibling (e.g. anti_whale_limit_detector, smart_money_inflow_tracker) to use instead, which keeps it off a 5.

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 trigger condition is clear: scan large transfers in the most recent blocks with a configurable USD floor. Negative scoping is present ('Ethereum only', 'other tokens are not included', 'not a live stream'), giving the agent explicit exclusions. It stops short of routing to an alternative when the caller needs history, other chains, or continuous monitoring.

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