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

No annotations are provided, so the description carries the full burden. It does useful work by disclosing the temporal limit ('up to a year of historical prices'), the date format, and the economic outputs produced. It omits what actually happens if the range exceeds a year (truncation vs. error) and whether payback is returned when capex is left null.

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 sentences, front-loaded with what is computed, then the use case, then the date-format caveat. No filler and nothing redundant.

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-value detail is not needed. However, for a six-parameter financial tool with no annotations, the description leaves gaps around the one-year window behavior, duration (MW/MWh) semantics, and the optionality of capex_per_kwh.

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 0% across six parameters, so the description must compensate. It clarifies zone semantics and the YYYY-MM-DD date format for start/end, and the mention of 'revenue per MW' and 'payback' implicitly ties to power_mw and capex_per_kwh, but power_mw, energy_mwh, and capex_per_kwh defaults/units are never explained.

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 computation (day-ahead arbitrage revenue), the resource (BESS in a European bidding zone), and the output unit basis (annualised revenue per MW, cycles, payback). This is clearly distinguishable from siblings like eu_power_prices or evm_gas_fees, which return raw market data rather than a project-economics metric.

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 when sizing or screening a battery project or comparing zones' gives concrete selection contexts. There are no explicit exclusions or named alternatives (e.g., when to prefer eu_power_prices for raw prices), so it stops short of a full when/when-not statement.

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