Signed market-hours / holiday / settlement answer (PAID $0.01)

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

The description adds real context beyond the annotations: the price (0.01 USD), the payment rail (x402/base/usdc on eip155:8453), and the remote route (POST /v1/market/calendar). It does not explain what the 'signed' payload attests to, whether payment settles before or after the answer, or how failures are charged. The annotations (readOnlyHint=false, openWorldHint=true) already signal a non-pure, open-world operation, and nothing here contradicts them.

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?

Two short lines, no filler: purpose first, then route and payment mechanics. It is efficiently sized, though the first line is a verbatim copy of the title rather than added information.

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?

An output schema exists, so return values need no explanation, but that is the only thing covered. For a paid, open-world tool with four undocumented parameters and numerous market siblings, the description omits usage conditions, parameter formats, and payment-flow behavior that an agent needs before invoking it.

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 four parameters (venue, nowEpoch, operation, tradeDate), so the description must carry the load and it carries almost none. The three answer types faintly hint at what 'operation' accepts, but venue, nowEpoch, and tradeDate formats (epoch units, trade-date encoding, venue identifiers) are entirely undocumented.

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 the resource ('market-hours / holiday / settlement answer') and adds that the answer is signed, so an agent can guess it returns trading-calendar data. But it is a noun phrase with no verb and it restates the title verbatim, and it gives no basis for distinguishing it from siblings such as v1_market_snapshot, v1_market_history, or v1_settlement_route_advice.

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?

There is no statement of when to call this versus any of the many market/settlement siblings, and no prerequisites or exclusions. The only actionable hint is the '(PAID $0.01)' tag, which tells the agent it costs money but not when the call is warranted.

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