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

Annotations already cover safety (readOnlyHint, idempotentHint, destructiveHint=false), so the bar is lower; the description adds genuine provenance and units beyond them, stating the data is copied from the official 'current visa pricing' table and that amounts are in AUD. It also discloses the full set of charge categories returned, though it doesn't state update cadence or staleness.

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 sentences, with the core purpose (charges for one subclass) front-loaded and the breakdown following. The long stream enumeration is informative rather than filler, though it makes the first sentence dense.

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?

There is no output schema, so the description carries the burden of describing returns, and it does so by enumerating the charge streams and second-instalment/STAC cases plus AUD units. It stops short of stating the exact response shape or error behavior for an unknown subclass, so it is complete but not exhaustive.

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 description coverage is 100% and the schema already documents both parameters (visaSubclass pattern/examples and the locale enum), so baseline is 3. The description adds only the granularity that a call covers a single subclass and its streams, which is marginal over the schema.

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 names a specific verb+resource (Home Affairs visa application charges) and scopes it to one visa subclass per stream, enumerating exactly what is returned (main applicant, additional applicant 18+/under 18, non-internet charge, second instalment, STAC). An agent can distinguish it from siblings like get_visa_processing_times or get_state_nomination 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?

Usage is implied by the phrase 'for one visa subclass,' which signals the required scope of the call, but no explicit when-to-use, when-not-to-use, or alternative tools are named. The agent must infer that this is the fee lookup rather than the processing-time lookup sibling.

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