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

Annotations already declare idempotentHint=true and destructiveHint=true, so the safety profile is known. The description adds genuinely useful merge semantics ('Only the sections passed are replaced; the others are kept'), which explains why a destructive replace is still idempotent and partial, and confirms a return value. It stops short of stating auth or permission requirements.

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 save action and the concrete fact types, and the merge rule is stated plainly. 'The adviser's answers need them' is an awkward, low-value sentence that slightly blunts an otherwise tight definition.

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 an output schema present, the description need not detail return values, and annotations cover the destructive/idempotent profile. The partial-update contract is the key behaviour an agent needs and it is stated; the main residual gap is that household_id and the required per-section fields are left entirely to the 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?

Reported schema description coverage is 0%, so the description must carry the load; it compensates partially by mapping the four content areas (health insurance premiums, tax bill, pillar 3a contributions, contract end dates) to the parameter sections. It says nothing about household_id, value formats (base currency, YYYY-MM-DD), or the per-section required fields.

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 (Saves) and resource (profile facts), and enumerates the four content areas so an agent knows what data belongs here. It contrasts implicitly with the read-oriented siblings (get_household_snapshot, get_household_answers) by describing a save operation, but never names a sibling to disambiguate it from complete_household_profile.

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 a usage trigger ('when the user has just given a fact that an answer needs') which is decent implied guidance for a save step in a flow. However there is no explicit when-not, no mention of alternative tools such as complete_household_profile, and the trigger is phrased in vague terms ('needs') rather than a concrete condition.

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