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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safe/stateless nature is covered structurally. The description adds that it returns 'total costs and recommendation,' which is mildly useful, but for a pure calculation there is little else to disclose; this meets the lowered bar rather than exceeding it.

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 the core purpose, then usage, inputs, and output in a compact set of sentences. The trailing pointer to list_bundles for 'finance-universal' calculators is mildly tangential but does not bloat the definition.

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?

An output schema exists, so return values need not be spelled out, and the description nonetheless summarizes them. For a 6-required-parameter, single-output calculation with full annotation coverage, the description is sufficient, though it does not address edge cases (e.g., zero residual value, rate of 0).

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 baseline is 3. The description recaps inputs ('car price, lease monthly cost, loan rate, ownership years'), but 'ownership years' does not map cleanly onto the schema's lease_months/loan_months fields, so it adds no real precision beyond the schema.

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 comparison verb ('Compare leasing vs buying') plus the resource ('a car') and the scope ('over the same period'). This is clearly distinguishable from neighbors like calculate_car_depreciation or calculate_belgian_car_advantage without opening any 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?

'Use for automotive purchase decisions' gives clear situational context for when to invoke it, and no sibling tool performs this exact lease-vs-buy comparison. However, it names no explicit alternative or exclusion condition, which is why it stops short of a 5.

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