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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered by structured data. The description adds the 2–5 car bound and the computed fields returned, but says nothing about error behavior (e.g. unknown id) or how missing cost inputs are handled.

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?

A single compact sentence with the scope front-loaded and the deliverable listed after the colon; no filler and nothing repeated from the schema. Length is well matched to a parameterized read-only comparison tool.

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 does enumerate what comes back, which is a genuine strength. But for a tool whose results depend on year, annual mileage and acquisition form, leaving those three parameters unexplained means an agent cannot reliably invoke it correctly in non-default cases.

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% across four parameters, yet the description only illuminates 'ids' (via the find_car reference and the 2–5 bound already encoded as minItems/maxItems). The three parameters that materially change the cost math — 'ar', 'milPerAr' and the 'anskaffning' enum (kop_ny / kop_begagnad / privatleasing) — are never explained, so the description fails to compensate for the coverage gap.

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 ('Jämför 2–5 bilar') plus the scope of the output ('total månadskostnad, kostnadsposter och skillnad mot billigaste'), which clearly separates it from single-car tools. It does not explicitly name how it differs from cost siblings like explain_costs or total_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?

The parenthetical '(id från find_car)' tells the agent where the required ids come from, which is real routing guidance. However, there is no statement of when to prefer this over my_monthly_cost, total_cost or explain_costs, and no exclusions or prerequisites for the comparison scenario itself.

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