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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, so the bar is lower, and the description adds genuinely useful context beyond them: per-call pricing ($0.09 USDC or prepaid credits) and the requirement to pass X-Payment / X-Payment-Tx / Bearer tokens in request headers rather than parameters. It does not cover rate limits, failure modes on unpaid calls, or empty-result behavior, which keeps it from a 5.

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 text duplicates the same content in a summary block and again in the [zh]/[en] vendor block, and '参数同左' points at nothing in this context. The payment-header sentence is the only tight, front-loadable piece; the rest is repetitive and poorly ordered.

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 no output schema, the description does cover return contents and billing/auth mechanics, which is the important missing piece for a paid report tool. The gap is parameter meaning: three undocumented inputs with 0% schema coverage are never explained, leaving an agent unable to choose sensible values for top, chain, or symbol.

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% across three parameters (symbol, top, chain), and the description only re-lists their names ('入参：symbol、top、chain') without explaining meaning, valid values, defaults, or interactions. '参数同左' ('parameters same as above/left') is a dangling reference that carries no information in a standalone MCP definition.

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 enumerates the report contents (per-coin supply, 1d/7d/30d change, share, chain split, mint/burn, plus 7-day issuance/redemption top 5), so an agent knows what it returns. It never explicitly contrasts itself with the sibling stablecoin-flow.flow_now, so the 'full vs. now' distinction is only implied by the word 'full'.

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 opening 'Ask "where is stablecoin supply moving"' gives a usage framing, which is better than nothing. However, there is no statement of when to prefer this over stablecoin-flow.flow_now or the whale/bridge flow siblings, and no prerequisites or exclusions beyond the payment note.

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