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

Annotations already cover read-only, idempotent, open-world, and non-destructive behavior. The description adds significant context beyond that: cost ($0.05 USDC or prepaid credits), payment transport in MCP headers (X-Payment / X-Payment-Tx / Authorization: Bearer fg_…), and AES-256-GCM encryption of records. It still leaves some ambiguity about whether the returned export is encrypted or decrypted and what happens on payment failure, so a 4 is appropriate.

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 definition contains useful information, but it is bilingual and partly repetitive, and it mixes vendor metadata with operational guidance. The critical payment-header instruction appears near the end rather than being front-loaded, and the opening “Ask …” phrasing is awkward.

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 low-complexity zero-argument paid export, the description covers the important context: cost, payment mechanism, encryption, and the absence of parameters. It does not describe the export format or snapshot contents in detail, but there is no output schema and the encryption/scope notes provide enough operational context.

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?

This is a zero-parameter tool, and the description explicitly confirms that with “入参：无” and “Args: none,” matching the empty input schema. With no parameters to explain, the baseline is 4.

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 the action and resource clearly: purchase a snapshot decryption license to read model-pricing records beyond the free twenty, returning AES-256-GCM encrypted records. It does not explicitly distinguish itself by name from sibling tools such as ai-2.preview or ai-2.status, so it falls short of a 5.

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?

Gives a concrete condition for use — reading beyond the free twenty records — and names an alternative for plaintext access: the origin detail gateway. It does not explicitly say when to use ai-2.preview or ai-2.status instead, nor does it state when not to use this tool, so it is not fully exhaustive.

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