List HACS pending upgrades

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

Annotations already declare read-only/idempotent/non-destructive, so the safety profile is covered; the description goes further by revealing the underlying `hacs/repositories/list` WebSocket command, the `pending_upgrade` filter that produces the result set, and the two distinct error shapes with their fields. That is exactly the kind of beyond-annotation context an agent needs to interpret failures.

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 effect, then segmented into Use when / Not for / Returns / Errors, which is easy to scan. It is somewhat long for a zero-parameter tool, and the Returns paragraph partially restates what the existing output schema already provides, but the error-shape detail earns its space.

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 no-parameter, read-only list tool with an output schema, the description supplies everything an agent needs: what it returns, the failure modes, and the correct sibling to use instead. Nothing material 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?

The tool takes zero parameters and the input schema is empty, so there is nothing for the description to disambiguate — baseline 4 applies. No parameter semantics are needed or possible here.

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 installed HACS repositories that have a pending upgrade') and distinguishes itself from the near-identical sibling by naming `hacs_list_hacs_repositories`. It even resolves a naming trap: the tool is called 'critical_updates' but the description says HACS has no separate critical severity here, so the agent won't over-interpret the results.

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?

Explicit 'Use when' clause ties it to the follow-up action (`hacs_update_hacs_repository`), and an explicit 'Not for' clause names the alternative (`hacs_list_hacs_repositories`). Both the selecting condition and the exclusion are stated, leaving nothing to inference.

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