List available HA updates

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is carried structurally. The description adds real context beyond that: it reads all HA states and filters to the update domain, extracts version/release attributes, and sorts pending updates first. This is useful mechanism disclosure, though it stops short of noting any rate limits or performance caveats of scanning all 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?

Front-loaded with the core action, then clean 'Use when'/'Not for'/'Returns' sections; every line has a clear role. The Returns field enumerates fields an output schema already exists for, which is mild redundancy, but the overall structure is efficient and readable.

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?

Given an output schema, full annotation coverage, 100% schema description coverage and 1 optional param, the description supplies everything an agent needs: what it scans, how it filters, what it excludes, and the alternative tools. Nothing required for correct invocation is missing.

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% and the single pending_only parameter is fully documented in the schema, so the baseline is 3. The description reinforces the sort behavior ('pending updates first') but adds no syntax or edge-case detail beyond what the schema already provides.

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+resource ('List Home Assistant's update.* entities, one per updatable component') and enumerates the covered domains (core, add-ons, HACS repos, custom components). It also explicitly distinguishes itself from supervisor_get_addon/supervisor_list_addons, so an agent can tell it apart from siblings 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?

Uses explicit 'Use when' and 'Not for' clauses: whole-instance update checking in one call, with the exclusion pointing to supervisor_get_addon and supervisor_list_addons for live Supervisor add-on state. When, when-not and alternatives are all present.

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