get_plant_status

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuinely non-obvious behavior: it discloses that load_power is a derived proxy on older firmware (plant AC output + grid power + third-party PV - AC EV charger power) rather than a measured register, which prevents the agent from misreporting the value. It does not mention polling/rate considerations, keeping 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?

The primary sentence front-loads the resource and its contents in a colon-delimited list with no filler. The second paragraph earns its place by qualifying one field, though the hard line break mid-sentence makes it read slightly awkwardly.

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?

For a no-argument, read-only snapshot tool with an output schema, the description is close to sufficient: the output schema supplies the field types and the description supplies the aggregation scope plus the one semantic trap (derived load_power). It omits alarm/mode enumeration semantics, which the output schema likely covers only as types.

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?

Zero parameters, so there is nothing for the description to disambiguate; the baseline for a no-param tool is 4. The field-level note about load_power is a return-value caveat rather than a parameter concern.

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+resource ('live overview of the whole system') and enumerates exactly what is returned: PV, battery, grid and load power, battery SOC, mode and active alarms. The 'whole system' framing distinguishes it from the narrower siblings get_grid_status, get_battery_status and get_inverter_status without the agent needing to open a 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?

'Live overview' implies a real-time snapshot use case, which implicitly contrasts with get_energy_totals (historical aggregates), but the description never states when to prefer the per-component siblings or when this aggregate is unnecessary. Usage is inferred rather than stated, so this lands at the minimum-viable level.

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