Install an add-on

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

Annotations cover the safety profile (readOnly=false, openWorld=true, idempotent=true, destructive=false), and the description goes well beyond them: it discloses that install downloads an image, reaches outside the HA instance/host, can take a while on slow connections, does not add repositories, and requires SUPERVISOR_TOKEN. Error shapes are enumerated.

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 purpose, then prerequisites, usage, returns, errors, and limits in clearly labeled blocks. Each section carries distinct information (endpoint, network behavior, token requirement, error payloads) with no filler.

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 single-parameter install mutation with an output schema present, the definition supplies everything an agent needs: prerequisites, side effects, auth requirement, latency caveat, and concrete error responses. Return values are only briefly noted, which is fine given the output 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?

Only one parameter (slug) and schema description coverage is 100%, so the schema already documents it thoroughly (including examples of where slugs come from). The description adds nothing new about the parameter itself, making the baseline 3 appropriate.

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 ('Install an add-on from its slug') and even names the underlying endpoint POST /addons/<slug>/install. It clearly distinguishes itself from the sibling lifecycle tools supervisor_start_addon and supervisor_stop_addon, which are explicitly called out.

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 (adding an add-on already visible in an installed repository) and an explicit 'Not for' clause routing the agent to supervisor_start_addon/supervisor_stop_addon for already-installed add-ons. No inference required.

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