Update a Home Assistant user

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

Annotations already declare destructiveHint=true and readOnlyHint=false, so safety is partly covered; the description adds genuinely new behavior: partial-update semantics, that is_active=false disables sign-in without deleting the account, and permission/ownership restrictions. It does not state reversibility or failure behavior, but adds solid context beyond the annotations.

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?

Four short sentences, front-loaded with the field scope, then partial-update semantics, the destructive effect, and the restrictions. Every sentence carries distinct information with no padding.

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 mutation tool with no output schema, the description covers the mutation scope, partial-update behavior, disabling effect, and restrictions, which is close to complete. Minor gaps remain (no statement about reversibility or error/refusal behavior beyond the ownership rule) but nothing essential 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?

At 67% schema coverage, the description enumerates the modifiable fields (name, role, active state, local-only) and explains the omit-to-keep behavior, which meaningfully supplements the schema. user_id and instance_id are only covered by their schema descriptions, so it doesn't fully compensate, but it adds value rather than repeating.

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 (Change/Update) plus the resource (user) and the exact field scope (name, role, active state, local-only). This scope cleanly separates it from credential/password siblings (ha_set_user_credentials, ha_change_user_password) and from ha_create_user/ha_delete_user without needing to name them.

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?

Gives real usage semantics ('Omit a field to leave it unchanged') and explicit exclusion conditions (cannot modify the owner's active state or a system-generated Supervisor user) plus the ha:config prerequisite. It stops short of routing the agent to a named alternative tool, so it is clear context rather than full when/when-not/alternative coverage.

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