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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so safety is covered. The description earns credit beyond that by disclosing scope details an agent wouldn't otherwise know: malus tax is included per Transportstyrelsen and the exact cost categories are folded into the result. It is silent on output shape, which keeps it from a 5.

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 dense sentences with no filler: the first defines the computation and its components, the second front-loads the input rule. Slightly long due to the component list, but every item carries information about what is modeled.

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 17-parameter, zero-required calculator with no output schema, the description should say what the result looks like (single monthly figure vs. per-component breakdown) and how defaults are chosen when nothing is supplied. It covers inputs at a conceptual level but leaves the return value and defaulting behavior unexplained, which matters given how many optional parameters exist.

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?

With 17 parameters and only 6% schema description coverage, the description has to compensate, and it partially does: it maps cost categories (värdeminskning, ränta, drivmedel/el, försäkring, fordonsskatt, service, däck, besiktning) onto parameter families and calls out the two mutually exclusive entry inputs (pris vs leasingPerManad). It gives no units or defaults for the remaining numeric parameters (ar, ranta, milPerAr, elpris, bensinpris/dieselpris), all of which are bare numbers in 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 verb and resource ('Räknar total ägandekostnad (TCO) per månad för valfri bil i Sverige') and enumerates the cost components included, so the agent knows exactly what is computed. It does not name the obvious computational siblings (compare_cars, explain_costs, my_monthly_cost), so it stops short of a 5.

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?

Adds one concrete input rule — 'Ange pris (köp) eller leasingPerManad (privatleasing)' — which implies the two usage modes (purchase vs private leasing). It never says when to pick this over compare_cars/explain_costs/my_monthly_cost, nor any prerequisites, so guidance is implied rather than explicit.

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