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

With no annotations, the description carries the full burden and does most of it: it discloses the operation is read-only, that the caller's own wallet sends the faucet call rather than the server, that the faucet pays a fixed amount once per cooldown, that next-draw-time is only returned "when readable", and that mainnet yields a not_on_mainnet error. It stops short of giving the actual cooldown duration or stating whether the balance/draw time is null when absent, so a small gap remains.

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-loads the two most decisive facts (TESTNET only, what is returned) and every clause carries information. It is dense and slightly run-on in the middle, with the onboarding chain and mainnet fallback packed into single sentences, but there is no filler to cut.

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, so the description must describe returns, and it does: the faucet call fields (to, data), balance, next draw time, and the ordered onboarding steps. It also covers the failure mode on mainnet, leaving nothing an agent needs in order to call this 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 description coverage is 0% for the single optional `account` parameter, so the description must compensate. It partially does by framing the output as "the account's balance and next draw time", implying `account` selects whose balance/draw time is read, but it never says the parameter is optional or that it defaults to the caller's own address, leaving the default behavior to inference.

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 concrete verb+resource: it tells the agent how to obtain the test settlement token (TestUSD, hUSD-test) and enumerates exactly what the response contains (faucet call, balance, next draw time, onboarding steps). It also positions itself against the sibling how_to_deposit by naming the mainnet counterpart, so an agent can pick between them without opening schemas.

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?

"TESTNET only" and "Mainnet answers not_on_mainnet (see how_to_deposit)" give an explicit when-to-use and an explicit when-not plus the alternative to use instead. The embedded onboarding chain (connect -> faucet -> deposit -> session key -> quote -> fill) further tells the agent where this sits in the workflow.

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