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

Annotations already mark this as read-only, idempotent, and non-destructive. The description adds valuable behavioral context beyond those: the $0.001 USDC cost per call, supported chains, bounded windows, and byte-identical equivalence to a specific GET endpoint. This is exactly the operational detail an agent needs to safely invoke the tool.

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?

The description is well-structured and front-loaded with the core purpose. It includes useful operational details like cost, chains, and an endpoint example. The byte-identical URL is long but serves as a precise, unambiguous example, so it earns its place.

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 an output schema present, rich annotations, and fully described parameters, the description covers the remaining essentials: cost, chain list, bounded window, and exact endpoint equivalence. The only notable gap is not explicitly routing the agent away from closely related sibling tools like chain_wallet_approvals.

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 chain, token, and blocks. The description adds an example request and clarifies the decoded output (owner/spender/amount), but it does not materially expand the meaning of the parameters themselves. Baseline 3 is appropriate.

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 clearly states a specific action and resource: approving events for one token over a short, bounded window, decoded to owner/spender/amount. The 'who just gave someone leave to move their USDC' phrasing makes the tool's purpose vivid and easily distinguishable from siblings like chain_wallet_approvals, chain_allowance, and chain_transfers_scan.

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?

The description gives clear context: use it for recent approval events for a single token, not for wallet-wide approvals or current allowance checks. It does not explicitly name alternatives or state when not to use it, but the 'one token' and 'short, bounded window' constraints make the intended usage reasonably clear.

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