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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses pricing ($0.003 USDC per successful call via x402 on Base/Solana/Arc), that failed calls are not charged, that sender/receiver labels are null for most addresses, and that the data window is constrained by a single RPC read. These are material traits an agent cannot derive from the annotations.

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 paragraph that front-loads the purpose before pricing and caveats; nearly every clause carries information. It is slightly packed with mixed concerns (data shape, cost, freshness) but wastes no sentences.

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 five parameters fully documented in the schema, an output schema covering the return shape, and the description adding cost, payment rails, label nullability and freshness limits, an agent has everything needed to call this correctly and predict the outcome.

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 the schema already documents defaults, ranges and per-chain block limits; baseline is 3. The description adds only marginal meaning ('where the chain has it' for tokens, Coinbase spot price for USD valuation) and does not override the schema's work.

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 names a specific resource and scope: large stablecoin/major-token transfers in the last few minutes across five named chains, with the returned fields (hash, block time, sender, receiver, amount, USD value) enumerated. An agent can immediately tell this apart from general tools like evm_transfers or crypto_candles.

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 by the scope ('last few minutes', 'sorted by value', 'one token contract read over public RPC, so the window is short'), but the description never states when to pick this over alternatives such as evm_transfers or crypto_orderbook. The 'information only, not financial advice' line is a disclaimer, not routing guidance.

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