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

Annotations include readOnlyHint=true, which is consistent with the description's processing of an input image without external state changes. The description adds meaningful context beyond annotations: the output format (masked_image field with base64), a cost note (30 points per call), and a legal usage requirement. It could have mentioned any rate limits or auth needs, but these are not obviously relevant. The added context is valuable and not redundant.

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 bilingual (English and Korean) and includes legal and cost notes, making it slightly longer than necessary. However, it front-loads the main purpose and then provides operational details in a logical order. There is no fluff, and each sentence carries meaning, though the bilingual repetition could be seen as slightly 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?

With only one parameter and no output schema, the description covers key operational aspects: what the tool does, input format, output field (masked_image) and encoding (base64), plus usage constraints. It does not enumerate the 'key fields' that are extracted, which could be important for agents to decide if the response meets their needs. Still, the description is reasonably complete for a single-parameter tool.

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 schema already describes the only parameter (image_url) with 100% coverage, including allowed formats and size limit. The description restates the format ('PNG 또는 JPEG') but does not add new semantic meaning beyond what the schema provides. According to the calibration, a baseline of 3 is appropriate when schema coverage is high and the description adds minimal extra parameter detail.

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 the verb 'extract' and the resource 'Korean alien registration card (residence card)', and specifies the action of masking the last 6 digits of the registration number. This distinguishes it from sibling tools like identity_document_id_card or identity_document_passport, which handle different document types. The purpose is unambiguous and specific.

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 indicates that a single PNG or JPEG image should be passed, and includes a legal prerequisite ('only use if you have a legitimate processing basis such as consent'). It does not explicitly name alternatives or state when NOT to use this tool, but the document type (alien registration card) and masking operation clearly differentiate it from siblings. The context is sufficient for an agent to decide when to invoke it.

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