check_key_transfer

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

Annotations declare a non-read-only, non-destructive, non-idempotent, open-world call; the description adds substantive context beyond that: it persists the key ('保存する') and explicitly notes the original device is not invalidated. That last clause is valuable disambiguation an agent could not derive from annotations alone.

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 compact sentences, front-loaded with the action and followed by the one caveat that matters. Nothing redundant.

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 not be described, and with no parameters the description covers the essential mutation behavior and side-effect scope. Minor gap: it does not state prerequisites such as authentication state or what happens on key mismatch.

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 takes zero parameters, so there is nothing semantic to explain and the baseline is 4. The description correctly focuses on behavior rather than arguments.

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?

Specifies the operation precisely: receive the key after smartphone approval, verify it against the registered key, and save it. A clear verb+resource chain. It does not explicitly distinguish itself from the sibling claim_key_transfer, so it stops 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?

The phrase 'after smartphone-side approval' implies a precondition and timing for when to call it. However, it never names or contrasts with claim_key_transfer or the email-login siblings, so the agent must infer which transfer tool to use.

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