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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely useful non-obvious behavior: fleet_rev_mtd is gross spot revenue over any window despite its name, avg_efficiency_pct is a capture rate and returns null when optimisation hasn't run, and commissioning units are excluded unless include_commissioning is true. It stops short of describing caching or volume but adds substantial context beyond the annotations.

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-loaded with the return payload, then caveats, then sibling routing in a single dense paragraph. Every clause carries information, though the field enumeration is long enough to be slightly heavy to scan.

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?

There is no output schema, so the description must and does explain the return fields and their edge cases (null efficiency, gross-revenue naming caveat). Combined with the date-window defaults and sibling routing, an agent has everything needed to call it correctly.

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%, so the baseline is 3, but the description adds real meaning: it explains the month-to-date default, that fleet_rev_mtd spans whatever date_from/date_to window is set, and that include_commissioning toggles the efficiency figure specifically. This goes beyond the schema's terse field notes.

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 (fleet-wide snapshot for the NEM battery fleet) and enumerates the exact metrics returned, so the agent knows precisely what this tool yields. It also names the two sibling tools it is not, distinguishing it from get_battery_detail and get_rankings.

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?

Explicitly routes the agent: 'For one battery use get_battery_detail; for a ranking use get_rankings.' The default window behavior ('covers month-to-date unless date_from and date_to are given') further clarifies when the tool applies without arguments.

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