ha-nexus-agent

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Set add-on options

supervisor_set_addon_options

DestructiveIdempotent

Replace a Home Assistant add-on's stored options with a complete object for programmatic configuration changes. Include all existing fields, as omitted ones are lost, then restart the add-on.

Instructions

Replace an add-on's stored options with the given object.

Calls POST /addons/<slug>/options as {"options": options}. Read current values via supervisor_get_addon, modify them, and send the full dict back — overwrites previous options entirely, so omitted fields are lost. A value left as the placeholder for a secret field is swapped for the real stored value first, so echoing it back unchanged never overwrites the secret — a list containing it must keep every item's order/count as read, or the call is refused rather than guessed. Once a placeholder was resolved, a Supervisor error strips detail (it can otherwise echo the rejected payload, secret included). Takes effect after supervisor_restart_addon. Refuses to run against nexus's own add-on — could otherwise lift its own restrictions.

Use when: changing an add-on's configuration programmatically. Not for: reading the current options first — use supervisor_get_addon; for changing nexus's own configuration — use the Home Assistant Supervisor UI instead. Returns: Supervisor's options-update result. Errors: {"error": "invalid_slug"} for a bad slug; self_addon_options_blocked for nexus's own add-on; redaction_marker_list_length_mismatch on a placeholder list-length mismatch; SUPERVISOR_TOKEN not set when the token is missing; {"error": "HTTP <status>"} on a schema-validation or placeholder read-back failure. Limits: does not apply until the add-on is restarted.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`slug`	Yes	Add-on slug whose options to set, e.g. from `supervisor_list_addons`.
`options`	Yes	Full options object to store, validated by Supervisor against the add-on's schema. Any field read via `supervisor_get_addon` and left out here is not preserved automatically — include the whole dict, not just changed keys.

Output Schema

TableJSON Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedv0.25.1Oct 4, 2026

addedInput schema / properties / options / description

Added value: +"Full options object to store, validated by Supervisor against the add-on's schema. Any field read via `supervisor_get_addon` and left out here is not preserved automatically — include the whole dict, not just changed keys."

addedInput schema / properties / slug / description

Added value: +"Add-on slug whose options to set, e.g. from `supervisor_list_addons`."

First observedv0.3.0May 3, 2026

TDQS

A4.8/5.0

Behavior5/5

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

Annotations only give the coarse profile (destructive, idempotent, not read-only); the description goes well beyond by explaining full-overwrite semantics, that omitted fields are lost, secret placeholder substitution rules, the list-order/count refusal condition, detail-stripping on error after placeholder resolution, and the self-add-on block. This is exactly the kind of behavioral context that prevents misuse.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loads the core semantic (full replacement) and then uses labeled sections (Use when / Not for / Returns / Errors / Limits) that make scanning easy. It is dense and long, but nearly every clause carries operational information; the secret-placeholder passage is repetitive in places.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With an output schema present, return values need no elaboration, and the description still enumerates error codes, the restart requirement, and the self-add-on guard. For a destructive mutation tool, an agent has everything needed to call it safely.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so baseline is 3, but the description adds real value: it clarifies that omitted fields are not preserved and that the placeholder value for secrets is resolved before write. It reinforces the schema's whole-dict requirement rather than adding new syntax, so it lands just above baseline.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Names a specific verb and resource ('Replace an add-on's stored options with the given object') and pins down the API operation (POST /addons/<slug>/options). It clearly distinguishes itself from the read path by naming supervisor_get_addon as the sibling that reads current values.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Has explicit 'Use when' and 'Not for' sections, each naming the correct alternative (supervisor_get_addon for reading, Supervisor UI for nexus's own config). The restart dependency is also stated, so an agent knows the ordering constraint.

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

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