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

Annotations already declare readOnly, idempotent, closed-world and non-destructive, so the safety profile is covered. The description adds real context beyond them: prices are in AUD and exclude the government charge, and it is the authoritative source for Tern's fees. It does not state how current the prices are or how an unhandled subclass behaves, which keeps it below a 5.

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, front-loaded with the payload contents, then the fee distinction and the authority claim. No redundant or filler wording; every clause carries information.

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 lookup with no output schema, the description enumerates what comes back (products, plans, inclusions, fees) and the currency. The only gaps are the no-filter default and empty-result behavior, which are minor and partly inferable from the optional parameter.

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 single optional subclass parameter is already documented at 100% schema coverage, including the example "820" and the "only the product covering this" semantics. The description restates filtering by visa subclass without adding format, default behavior, or what happens when the filter matches nothing, so baseline 3 applies.

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 resource (Tern's products, partner visa plans, inclusions and AUD service fees) and explicitly draws the boundary that separates it from the sibling fee tool: fees are "separate from the government charge." An agent can select this over get_visa_fees without opening either 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?

Gives a strong directive on when to use it — "The only source to quote Tern's prices from" — and explains the filter usage ("Filter by visa subclass"). It stops short of naming when not to use it or what to use for government charges by name, but the exclusion is stated.

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