Add a custom HACS repository

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

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=true, openWorldHint=true), and the description adds traits annotations cannot express: the ha:config authorization requirement, the scope of the mutation ('only registers it'), and the critical quirk that HACS reports false success so the tool self-verifies by re-listing repositories.

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?

Two tight paragraphs: the first covers action, inputs, and the prerequisite follow-up; the second covers the silent-failure verification. Front-loaded and largely waste-free, though the parenthetical category list duplicates the schema's enumeration.

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?

With no output schema, the description compensates by explaining the observable outcome and the confirmation mechanism, plus prerequisites and the required follow-up call. An agent has everything needed to invoke it correctly and interpret the result.

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 the schema already documents repository, category, and instance_id semantics in detail. The description's category examples and 'owner/repo' format restate schema content rather than extending it, so the baseline of 3 applies.

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 ('Add a custom repository to HACS'), states the identifier format ('owner/repo' or URL) and the category taxonomy, and explicitly distinguishes itself from the sibling ha_hacs_download_repository by clarifying it only registers rather than installs.

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?

It states the exact follow-up needed ('call ha_hacs_download_repository afterwards to actually install it') and the condition that selects this tool (a fork, private project, or repo not in the default store). The auth prerequisite 'Requires ha:config' further scopes when the call will succeed.

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