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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds genuinely new behavioral context: the country-fallback pricing rule with the result flagging it, coverage information returned for uncovered places, and an explicit disclaimer that figures are modelled estimates rather than supplier quotes or booked-wedding prices.

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?

Four sentences, front-loaded with the core promise and then the fallback and output-shape details, with no filler. The fallback rule ('priced at its country and the result says so') is stated twice across the definition, which is minor redundancy rather than bloat.

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 contract and does so well: line-by-line breakdown, a typical total, the range most weddings land in, and coverage info when a place is not indexed. Combined with the modelled-estimate caveat, an agent has everything needed to call it correctly.

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%, so the schema already documents all four parameters including the destination-versus-country rule and the style default. The description restates the destination fallback semantics but adds no new syntax or format detail beyond what the schema provides, which is the expected baseline when the schema does the heavy lifting.

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 states a specific verb and resource (estimates a whole destination wedding budget in USD) and scopes it by guest count, place and style tier from a named cost index. It distinguishes itself from cost-adjacent siblings like get_alcohol_estimate, get_guest_travel_estimate and get_who_pays_split by being the whole-budget estimator.

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 clarifies the input selection rule (accepts a destination or a country; a destination without its own row is priced at its country) which is useful usage guidance. However, it never names an alternative tool or states when not to use this one (e.g. versus get_alcohol_estimate for a component), so routing is left to inference.

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