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

Beyond the readOnlyHint and openWorldHint annotations, the description adds that the call costs 0.001 USDC, performs no external data lookup, and returns specific fields (time, rail, network mode, capabilities). It also mentions that the result may vary by 'challenge' (aligning with openWorldHint). This context is valuable and does not contradict annotations.

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 a single paragraph that efficiently packs cost, output fields, network options, receipt details, and terms. It is not overly verbose, but the structure could be improved by front-loading the main purpose more clearly; it currently mixes output details with terms and price, yet remains reasonably concise.

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?

Despite having no parameters and no output schema, the description provides a solid overview of what the tool returns, its cost, network options, and terms. It does not cover error handling or prerequisites, but for a simple read-only check, it is fairly complete.

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 has no parameters, so the input schema fully covers parameter semantics (baseline 4). The description adds nothing about parameters, but since there are none, this 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 it is a payment integration check that returns time, rail, network mode, and free/paid capabilities, and it specifies the cost and that no external data lookup occurs. While it distinguishes itself from some siblings by mentioning 'no external data lookup', it does not explicitly name alternative tools, so it is clear but not explicitly differentiated.

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 no guidance on when to use this tool versus its many siblings (e.g., cheapest_settlement_chain, check_payment_terms). It only mentions business/professional use and availability of terms, but no context about when it is the appropriate choice or when to avoid it.

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