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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuine context beyond that: the output set (total, share of take-home pay, weeks of saving, cash by holidays, spend limit, per-person budget), the provenance ('Same math as the compoundmint.com holiday budget calculator') and the educational disclaimer. Without an output schema, this narrative of the return values is the main value add.

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?

Front-loaded with a clear trigger and examples, then a compact result enumeration. Slightly long due to three quoted examples and a run-on output list, but every clause is informative rather than filler.

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 9-parameter read-only calculator with no output schema, the description covers trigger, inputs contributing to the total, and the shape of the results, which is enough to invoke it confidently. It does not explain how optional inputs like monthly_income or weekly_savings change the output, but the schema defaults make that low-risk.

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 coverage is 100%, so all 9 parameters including their units and defaults are already documented in the schema. The description confirms the semantic intent of two of them ('people x budget per person') and the derivation of weeks_left, but adds little else 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 first sentence names a specific trigger scenario and quotes three real phrasings, and the second states exactly what the tool computes (gifts + travel + food + decor) and what it returns. It is clearly distinguished from siblings like calculate_savings_goal or calculate_debt_payoff by naming the holiday domain and the exact output set.

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?

The description opens with an explicit 'Use when...' trigger, gives example user utterances, and notes the negative scope ('Educational only, not financial advice'), which is the key boundary for a finance tool. The only small gap is that it does not name a specific sibling as the alternative for a non-holiday budgeting question.

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