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

The description adds real context beyond the annotations by describing the shape of the result (per-guest math, contingency line) and the scope boundary. However, with readOnlyHint=false declared, an agent could reasonably wonder whether the estimate is persisted or creates state; the description never says it is a pure calculation that writes nothing.

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 trigger condition and closed with a clean exclusion. The parenthetical category list is slightly long but it doubles as a preview of the output, so it earns most of its space.

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?

Return values needn't be explained since an output schema exists, and the two headline inputs are covered. But a 5-parameter, zero-required, zero-description schema with region/style/priority modifiers leaves the agent guessing how those knobs change the estimate — the description should close that gap and doesn't.

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 0% and the description only implicitly covers two of five parameters (budget by 'total wedding budget', guest count by 'guest count'). It never explains style, region, or — most importantly — how the `priorities` list (max 3) reweights the split, which is the parameter most likely to be misused.

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 verb (estimate/split) and resource (wedding budget) plus the concrete output shape: category-by-category split, per-guest math, contingency line. The enumerated categories and the explicit exclusion of spending tracking make it unmistakable against the timeline/seating/layout siblings.

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 an explicit trigger ('when someone gives a total wedding budget, a guest count, or both') and an explicit anti-pattern ('Do not use for tracking actual spending or vendor payments'). It stops short of naming an alternative tool for that excluded case, so it's strong but not a full routing rule.

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