List helper entities

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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint=false), so the description only needs to add context — which it does by disclosing the implementation path (`ha.get_states()` over HTTP followed by domain filtering), implying a full state read rather than a targeted query. It doesn't mention pagination or payload size, which is the only remaining gap.

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 core action in the first sentence, then structured labels (Use when / Not for / Returns) that let an agent skim. No filler sentences; every clause carries routing or behavioral information.

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?

The description covers purpose, routing, and the shape of the return value for a zero-parameter read tool. Even though an output schema exists, the brief 'list of dicts with entity_id, state, attributes' note removes any ambiguity about what a helper record looks like.

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 there is nothing for the description to disambiguate — the baseline of 4 applies. The description's mention of filtering by domain reinforces that no filter input exists here, which is the one thing an agent might otherwise expect.

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 (list) and resource (helper entities) and enumerates exactly what counts as a helper by naming all eight domains. It explicitly differentiates itself from the sibling `entities_list_entities`, so an agent can choose between them without opening either 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?

Contains explicit 'Use when: browsing which helpers exist and their current values' plus a 'Not for' clause naming the alternative (`entities_list_entities` with `domain` set) for the excluded case. Both the positive and negative routing conditions are given.

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