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

Annotations only supply readOnlyHint and openWorldHint; the description adds the material behavioral facts an agent needs: the exact price ($0.005 USDC per call via x402, an auth/payment requirement), the granularity of the response (best route, all route prices, $1,000 sell impact, thin-liquidity and pool-disagreement flags), and the quote methodology. It stops short of saying what happens when no pool exists or how stale quotes can be.

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 the core purpose, then supporting detail, then cost. Every clause carries information, though the deep parenthetical nesting (pool tiers inside the source list inside the price sentence) makes it dense enough to require a second read.

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 no output schema, the description must describe returns, and it does so concretely (best route, every route's price, $1,000 price impact, liquidity/disagreement flags). Combined with explicit pricing and sourcing, this is nearly complete for a single-parameter read tool; only error/edge-case behavior is 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?

Schema coverage is 100% and there is only one parameter, so the schema already fully documents the address field, making 3 the baseline. The description adds only marginal meaning by scoping it to Base ERC-20 contracts and implying tokens must have a DEX pool to be priced.

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 ("Live USD price of any ERC-20 token on Base") and immediately identifies the data source (Uniswap v3 0.05/0.3/1% pools, Aerodrome, USDC/WETH pairs, Chainlink conversion). This is clearly distinguishable from siblings like base_token_check (safety) or base_portfolio (holdings) without opening a schema.

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 description establishes this is a pricing lookup tool, so an agent can infer it should not be used for contract safety or balance queries. However, it never explicitly names an alternative sibling or states when-not to use it (e.g., unsupported tokens with no pool).

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