List zones

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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely non-obvious behavior: it scans ALL HA states and filters down to zone.* entities, then projects each to a slim attribute set. That implementation detail (broad read, filtered projection) is useful context the annotations do not convey.

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 purpose, then mechanism, then usage, then return shape — a clean structure with no filler. The closing "as described above" is mildly redundant since the projection was just enumerated, costing it a point.

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 zero-parameter, read-only list tool with an output schema present, the description covers purpose, filtering behavior, usage trigger and return shape, so nothing an agent needs to invoke it correctly is missing. The return-value sentence is technically duplicative of the output schema, but harmless.

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 per the rubric the baseline is 4. There is nothing for the description to disambiguate, and it correctly does not invent parameter semantics.

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 ("List all zone entities") and immediately narrows scope with "with their common location attributes," which distinguishes it from zones_get_zone (single zone) and zones_list_persons_in_zone (occupancy). An agent can route correctly 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?

The explicit "Use when: you need every zone's location and radius, e.g. before checking who is inside one" gives a concrete trigger and even hints at the natural follow-up tool (zones_list_persons_in_zone). It stops short of naming alternatives or exclusions explicitly, so it falls just below a 5.

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