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

Annotations already declare readOnlyHint/idempotent/non-destructive, so the bar is low, yet the description still adds real behavioral context: the per-call price (16¢), the valuation source used (`land_value_source: land_valuation`), the understatement caveat for multi-property owners, and the failure mode of `available: false` outside NSW or without a valuation. It also documents that principal_residence always yields 0 with a reason.

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 key qualifier is bolded and front-loaded, and the second paragraph moves cleanly from caveat to availability to price. It is dense but nearly every sentence carries information; the only slight waste is restating the calculator equivalence twice ("same calculation as" and "Priced as the calculator plus the land values").

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 must carry return semantics, and it does cover the important cases: `available: false` for unsupported/no-valuation properties, the 0-with-reason exemption path, and the `land_value_source` marker. It does not describe the remaining shape of a successful result (e.g. the amount or rate breakdown), which is the one remaining gap.

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 80%, so the schema already explains gnaf_id, foreign, owner_type, assessment_date, and principal_residence. The description adds only indirectly — that the state is derived from the property and the land value comes from its latest valuation — but says nothing extra about the boolean or date parameters beyond what the schema states. 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?

The description names a specific resource and scope: annual land tax on this specific property as if it were the owner's only taxable land, computed from its latest land valuation. It explicitly contrasts itself with the sibling `/calculators/land-tax`, so an agent can distinguish the two 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?

It states exactly when to use this tool (single-property, sole-holding scenario) and when not to (an owner with other land should sum land values and use `/calculators/land-tax`). It also gives an availability precondition — NSW only, and `available: false` otherwise — which is the kind of routing guidance agents need.

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