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

Annotations already declare readOnlyHint, idempotentHint and non-destructive, so the safety profile is fully covered and this is a pure-computation tool with little else to disclose. 'Returns cost and hours' adds a light output summary, but the description does not explain defaults (price_kwh=0.25, target_pct=80) or edge behavior such as current > target.

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?

Front-loads the core purpose in the first sentence and packs inputs/returns into a compact enumeration. The trailing list_bundles pointer is mildly extraneous but short and does not bury the key information.

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 values need not be described, and all four parameters are schema-documented. However, the description's mention of a nonexistent 'charger kW' input leaves the parameter story inconsistent, and nothing explains the charging-time model or the effect of default values.

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 100%, so the schema alone earns a baseline of 3, but the description actively introduces confusion: it lists 'charger kW' as an input, and no such parameter exists in the schema (only battery_kwh, current_pct, target_pct, price_kwh). Naming a nonexistent input misleads an agent preparing the call.

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 ('Compute electric vehicle charging cost and time to full'), which unambiguously separates it from generic siblings like calculate_electricity_cost or calculate_fuel_cost. The scope (cost + charge time) is concrete and an agent could route to it without opening the schema.

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 for EV trip planning' gives a domain hint but no when-not conditions or named alternatives among the many cost/energy siblings. The 'See list_bundles for related energie calculators' pointer is a discovery cross-reference, not usage guidance for selecting this tool over calculate_electricity_cost.

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