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

With no annotations provided, the description carries the disclosure burden. It does reveal the mutating nature ('Create') and the expected result (BTCPay checkout URL), which is useful. However, it does not disclose payment order lifetime, expiry, idempotency, or whether funds are captured immediately.

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?

A single sentence communicates action, resource, and output with no filler. The most important information is front-loaded.

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 tool with one optional integer parameter and no output schema, this description captures the core call model: create an order, receive a BTCPay checkout URL. It is slightly thin on response details and edge cases, but the low complexity means nothing essential is missing for 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?

Despite 0% schema description coverage, the description connects 'credits' to 'ECHO credits', giving the single optional parameter some semantic context. It does not explain the default of 50, min/max values, or how credits map to payment amounts, relying mostly on the schema's type/default.

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 uses a specific verb ('Create') and a specific resource ('a payment order for ECHO credits'), and the parenthetical 'BTCPay checkout URL' makes the output concrete. This clearly differentiates echo_order from siblings such as echo_tts and echo_voices, which are about text-to-speech and voice listing, not payments.

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 phrase 'for ECHO credits' implies the tool is used when a user needs to generate a payment/checkout flow to acquire credits, but the description does not explicitly state when to choose this over alternatives or mention prerequisites. There are no exclusions or alternative-tool references.

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