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

No annotations are provided, so the description carries the burden. It discloses the tool's read-only informational nature and language behavior (en/vi), but it does not describe the output format or whether it returns text only.

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 dense but efficient, packing onboarding flow, audience, and free-vs-key distinction into two sentences. The Vietnamese repetition adds redundancy but is intentional for bilingual support.

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 simple no-output-schema tool, this description covers audience, workflow, prerequisites, and parameter semantics. The only missing piece is what the returned content looks like, which is minor for a guide.

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 schema already documents the lang parameter. The description adds helpful context about the default ('en') and the purpose (selecting guide language), which is slightly more than the bare schema description.

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 this is an onboarding guide that walks new users through the account-creation-to-purchase flow. It also distinguishes itself from siblings like topup_guide by explicitly being the 'Ideal first call for new / international users.'

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?

It explicitly says when to use it ('first call for new / international users') and what value it provides (which tools are free vs. need an api_key). The lang parameter guidance is also directly useful for choosing between the English and Vietnamese versions.

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