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

No annotations are supplied, so the description carries the full burden. It does disclose the read-only nature ('read from the contracts'), the data source, the freshness ('right now'), and that the call is free — useful beyond structured fields. It omits failure modes (what happens if a contract read reverts), caching behaviour, and whether the returned domain data is chain-versioned.

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 front-loaded sentence covering subject, method, payload, and cost, with the terse 'Free.' tail. Nothing redundant, though the run-on listing of payload items slightly blurs scanning.

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?

For a zero-parameter read tool with no output schema, the description is the only place the return payload can be described, and it does so concretely: USDC and EURC total supply, addresses, EIP-712 domains. That is enough for an agent to decide to call it and to interpret the response.

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?

The tool takes zero parameters, so there is nothing to disambiguate; baseline is 4. The description correctly implies no arguments are needed by framing the call as a fixed snapshot read.

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 resource set and source: stablecoin supply on Arc read from the contracts, naming USDC and EURC plus their addresses and EIP-712 signing domains. An agent can tell this apart from price/market siblings like arc_price or arc_token_info, though the description never explicitly contrasts with them.

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: if you need supply numbers, token addresses, or signing domains, call this. There is no explicit when-not guidance and no mention of the neighbouring tools (arc_token_info, arc_allowance, arc_payment_check) that an agent might confuse it with. 'Free' is the only cost/eligibility hint.

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