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

Beyond the readOnlyHint/destructiveHint annotations, it discloses the pricing model ($0.005/call, first 25 free, failed calls free), that repeats are not free (consistent with idempotentHint=false), the on-chain data provenance (deepest Uniswap v3 pool vs USDC/WETH), and the graceful-degradation behavior (unpriced list instead of failing). That is unusually rich context an agent cannot get from annotations alone.

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?

Front-loaded with scope and covered chains, then pricing and safety, so the most decision-relevant facts come first. It is dense and long for one paragraph, but nearly every clause (chains, pool source, unpriced fallback, cost, free retries) carries 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?

There is no output schema, and the description compensates by naming what comes back: price, pool, reserve, and a thin-liquidity flag, plus the unpriced fallback list. Combined with the billing and safety notes, an agent has everything needed to call it and interpret the result.

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 description coverage is 100%, so all three parameters are already documented, including the enum values and the 1-20 token limit. The description mostly restates the accepted formats (tickers, 0x addresses, chain names) and adds no syntax or mixing rules beyond what the schema already says, 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?

The description opens with a specific verb-resource-scope statement: USD prices for up to 20 tokens in one call, by ticker or ERC-20 address, across four named chains. It clearly distinguishes itself from the singular sibling price_token by emphasizing the batch/basket nature and the 'one call' framing.

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 states a concrete usage context ('value a basket of tokens or refresh a watchlist in one paid call') and gives a worked example (symbols=ETH,BTC,AERO), which is enough to pick this over the single-token sibling. It stops short of an explicit 'use price_token instead when you only need one token' exclusion.

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