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

Annotations only declare readOnly and openWorld. The description adds material behavior the annotations cannot convey: exact cost ($0.002 USDC per successful call via x402, payable on Base/Solana/Arc), that failed calls are free, and a data-quality caveat that unpriced transfers are counted but excluded from USD sums.

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 what the tool returns, then scope boundary, then data caveat, then pricing. Four dense sentences with no filler; each one adds 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?

An output schema exists, so return-shape explanation is unnecessary. Given a one-parameter, read-only tool, the description covers source, window semantics, aggregation caveat, and cost model — everything an agent needs 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% and the single 'limit' parameter already documents the 1–100 range and default 50. The description restates the same range without adding format or edge-case guidance, so the schema is doing the work. 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?

Specific verb+resource: cross-chain transfer volume from Wormholescan (Wormhole), grouped by source and destination chain over the newest N transfers. The scope wording clearly separates it from chain-level TVL or trend tools in the sibling list.

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?

Explicitly states the usage boundary: 'A recent window, not total bridge TVL or long-term trends,' which steers the agent away from using it for TVL/trend questions. It stops short of naming the exact alternative sibling (e.g., defillama_tvl_oracle), so it isn't a full when/when-not/alternative statement.

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