List entities

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds that results are 'current state' and implicitly compact (include_attributes defaults to false), but says nothing about pagination/limit behavior, result ordering, or auth/session constraints beyond what the schema states.

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?

Three tight sentences with the core purpose front-loaded; the filter list follows immediately and the routing sentence closes. The last sentence is slightly promotional ('fastest way') but still earns its place as usage guidance.

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 six-parameter, zero-required read tool with no output schema and thin annotations, the description covers the discovery use case and the primary filters adequately. Gaps remain around return volume/pagination and the instance_id cross-home safety behavior, which live only in the schema.

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 all six parameters are already documented, and the baseline is 3. The description reinforces domain ('light'), area (id or name) and search semantics but adds no syntax or format detail beyond the schema, and never mentions limit, instance_id, or include_attributes.

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?

The description gives a specific verb+resource ('List entities') plus the scope modifier 'with their current state,' which separates it from a single-entity read like ha_get_state. It never names the near siblings (ha_get_entity_registry, ha_list_devices), so an agent must infer the boundary itself, keeping this just short of a 5.

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 final sentence gives a clear context: use this to discover what exists before calling services or editing automations, which is a genuine when-to-use statement. It offers no explicit exclusions or named alternatives (e.g. 'for one entity use ha_get_state'), so it is clear but not exhaustive.

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