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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered; the description adds genuinely non-structured context: the exact cost per call (0.0050 USDC, first free), the scope of what is excluded (fees, gas, slippage), and the precision of the returned spread. It stops short of rate limits or latency, which keeps it off 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?

Three short sentences that are front-loaded with the core action, then the exclusions, then the price. No filler, and each sentence carries distinct decision-relevant information.

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?

No output schema exists, and the description compensates by naming the return fields (gross spread bps, cheaper side) and the supported chain and venues. With a single optional parameter and read-only annotations, this is nearly complete; only error behavior on unsupported pairs and freshness/latency of the quote are unaddressed.

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?

One optional parameter with 100% schema description coverage, so the schema already states that only "WETH/USDC" is supported. The description repeats the pair restriction without adding format, casing, or defaulting semantics, 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?

Names a specific verb (read on-chain spot price) and resource (WETH/USDC on Uniswap v3 and Aerodrome v2 on Base), plus the exact output (gross spread in bps and cheaper side). An agent can tell precisely what this returns without opening the schema, and no sibling tool overlaps it.

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?

Usage is implied rather than stated: the tool is evidently for screening arbitrage spreads, and the caveat that fees, gas and slippage are excluded implicitly signals it is a pre-trade screen, not a profitability calculation. There is no explicit when-to-use, when-not-to-use, or pointer to a sibling for the follow-up cost analysis.

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