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

Annotations only declare readOnlyHint=true; the description adds real behavioral context — the 2 km route corridor, the fallback national ranking, VAT-inclusive pricing, and a `source_url` per result for citation. It omits rate-limit specifics in the description (they appear only in the schema's route note), which keeps it short of 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?

Three dense sentences, front-loaded with the resource and unit of measure, then the three input modes, then the return shape. No filler or restatement of the name.

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 carries the burden of describing returns and does so adequately (network price ranking, cheapest stations, source_url). Minor gaps remain around result ordering and the rate-limit behavior of route queries, which an agent might want before calling.

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 the baseline is 3, but the description adds genuine meaning by explaining the interaction between `city`, `route`, and the neither-given case — semantics the per-parameter schema text does not convey. It does not discuss `limit` behavior beyond what the schema documents.

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 resource and scope: cheapest public EV charging in Lithuania, priced in EUR/kWh incl. VAT, segmented by power class. This clearly differentiates it from siblings like find_stations (location lookup) and charging_cost (per-session cost).

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?

Explicitly describes three invocation modes: `city` for local cheapest stations, `route` {from,to} for corridor results within 2 km, and neither for the national network ranking. It does not, however, say when to prefer this over siblings such as charging_cost or operator_tariffs.

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