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

Annotations already declare readOnly/idempotent/openWorld/non-destructive, and the description adds real behavior beyond them: zh-CN/zh-TW return Chinese names alongside official English in nameEn/streamEn, Home Affairs notes stay in English, and the endpoint preserves sources, conditions and pagination. It stops short of describing rate limits or result sizes.

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?

Three dense sentences that are front-loaded with the core purpose, then the parameter, then the locale/output behavior. Every sentence carries information, though the closing sentence about 'English natural-language text, preserving sources, conditions and pagination' is slightly loose.

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 no output schema, the description carries the return-value burden and does so: percentiles, per-subclass/stream breakdown, publication date, and localized name fields. Annotations cover the safety profile, so the definition is nearly complete for a two-parameter read 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?

Schema coverage is 100%, so the baseline is 3, but the description adds semantics the schema does not spell out — that omitting visaSubclass lists every subclass and includes Home Affairs notes, and that locale governs name language plus the URL prefix. That is genuine added meaning over the enum and pattern.

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 precise verb+resource: Home Affairs global visa processing times broken down into 25/50/75/90% finalisation day counts per visa subclass and stream, plus the Home Affairs publication date. This is unmistakably distinct from siblings like get_visa_fees or get_visa_condition, so an agent can route without opening any schema.

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?

Explicitly describes both invocation modes: pass visaSubclass for a single visa (returned with Home Affairs notes), or omit it to list every subclass. That is clear operational context, though it does not name any alternative tool or state when a different tool should be preferred.

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