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

With no annotations supplied, the description has to do the behavioral work. It does disclose two useful facts: the call has a cost ($0.007) and the output names the winning venue plus the exact dollar delta versus the others. However, it never states that this is a read-only/advisory computation and not an order placement, nor whether the underlying prices are live or stale, nor anything about rate limits — material gaps for a tool invoked immediately before trading.

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?

One dense but well-ordered sentence that front-loads the price and the when-to-use trigger before the mechanics, followed by a short example. Every clause carries information, though the em-dash-heavy phrasing is harder to scan than a plain lead sentence would be.

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 three-parameter, no-output-schema, no-annotation tool, the description covers the cost, the trigger, the venue set and the shape of the return value. What remains unspecified — quote freshness and whether the result is guaranteed executable — is meaningful but not blocking for correct invocation.

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%, with types, enums, defaults and ranges all documented, so the baseline is 3. The trailing "Params: coin=BTC, size_usd=5000, side=buy" adds only a sample invocation and actually cites size_usd=5000 while the schema default is 1000, adding no real semantic meaning beyond the schema.

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 states a specific action and resource: it compares fee-adjusted net cost across Kraken, Coinbase and Hyperliquid for a given coin/size/side and returns the cheapest venue plus the dollar saving. That is far more informative than a restated name. It stops short of naming how it differs from siblings such as arb_spread or execution_window_optimizer, but the purpose itself is unambiguous.

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?

"Call this before executing a trade so you don't overpay in fees" gives a clear trigger condition and a reason, which is unusually actionable. There are no explicit exclusions (e.g., when to skip it, what to do for venues it doesn't cover) and no alternatives are named, so it falls 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.