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 genuinely non-obvious behavioral context: prices are operator-reported flat/ad hoc rates, exclude subscription and app tariffs, and are segmented by defined power classes (AC ≤22 kW, DC <50, 50–149, ≥150 kW). No rate limits, freshness/staleness of the data, or update cadence are stated.

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?

The purpose is front-loaded, but the body is a dense laundry list of returned metrics crammed into two long sentences. Since an output schema exists, itemizing every metric (including repeating the name finwire_ev_charging_price_index) spends budget on return-value detail the agent can already see. The scope caveat and network behavior are the parts that actually earn their place.

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 an output schema and full annotation coverage, the description only needs to convey scope, exclusions, and parameter effects, and it does all three. The market/geography boundary (Poland, UDT EIPA register) and the subscription-tariff exclusion are clear. Minor gaps are data vintage and whether the index reference implies another tool is needed for the raw index.

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% and the single parameter is documented as a network slug with examples, so the baseline would be 3. The description goes beyond the schema by explaining the semantic effect of supplying it: the response becomes that network's price list by power class plus its price changes, rather than the whole-market aggregate.

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 description names a specific resource (EV charging prices in Poland, UDT/EIPA ad hoc tariffs) and enumerates the exact breakdowns returned: median price per kWh by power class, AC vs DC, cheapest/expensive networks, per-minute fee share, and price changes. This is far more specific than a sibling like get_ev_charging or get_energy_prices. It stops short of explicitly contrasting itself with those siblings, so an agent must infer the boundary from the register/price-metric wording.

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?

It gives a clear usage context ("for a driver without a contract") and a scope exclusion that matters for interpretation ("Subscriptions and app tariffs can be cheaper and are not included"). The "With network:" clause tells the agent what changes when the optional parameter is supplied. It lacks explicit when-to-use-this-vs-sibling routing (e.g. find_ev_chargers for locations, get_energy_prices for wholesale), leaving that to inference.

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