get_energy_totals

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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses a real operational prerequisite (Modbus protocol V2.5+ firmware) and the failure mode (unsupported registers appear in `errors`). That is meaningful context an agent could not derive from annotations alone, though no rate-limit or caching behavior is mentioned.

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 short sentences, front-loaded with the resource and payload categories, followed by the firmware caveat. Every clause carries information; no filler.

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 present, return values need not be spelled out, yet the description still adds the non-obvious `errors` field semantics and the firmware gate. For a zero-parameter read tool this is close to complete, missing only the error/empty-state behavior when the firmware is too old.

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?

The tool takes zero parameters, so the baseline is 4. The description correctly implies no filtering input is needed for this aggregate read.

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 (plant energy counters in kWh) and enumerates the sub-categories covered: PV, load, battery, grid import/export, EV charger. This is clearly distinct from status-oriented siblings like get_plant_status or get_battery_status, though it does not explicitly name a sibling it should not be confused with.

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?

Usage is implied by the content — an agent can infer this is the cumulative-totals tool rather than a live-status tool. However there is no explicit when-to-use/when-not statement nor any reference to alternative tools for per-device counters, leaving routing to inference.

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