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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds a meaningful behavioral trait beyond that: the check is structural, not an authoritative Dukcapil lookup, so an agent knows a positive result does not mean the identity exists. It stops short of saying what 'parse' extracts.

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 short sentences with zero filler: the action and constraint come first, followed by the disambiguation caveat. Every clause earns its place.

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 one-parameter, read-only, no-output-schema tool, the definition covers what is needed to call it correctly and to interpret a success as structural validity only. The only gap is that 'parse' is never unpacked — which components (province, birth date, gender) come back is left unknown.

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?

Schema coverage is 100% and the single parameter is documented as a '16-digit NIK' in the schema itself. The description's '(16-digit ID)' merely restates that constraint without adding format nuances (spaces, dashes, leading zeros). Baseline 3 is appropriate when the schema does the heavy lifting.

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 a specific verb pair (validate and parse) on a specific resource (Indonesian NIK, 16-digit) with an explicit scope qualifier. It does not name any sibling, but the domain ('NIK format check, not registry verification') is unambiguous enough to separate it from validate_npwp, validate_phone, and generate_dummy_nik.

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 clause 'Not Dukcapil verification' implicitly tells the agent when this tool is and isn't appropriate, which is useful. However, there is no explicit guidance such as 'use this to check format before storing a NIK' or a pointer to generate_dummy_nik when a fake value is wanted, so routing to siblings is left to inference.

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