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

The description adds meaningful behavioral context beyond the annotations: it clarifies that entries are replaced or appended by id, that removals are entry-scoped, that expectedVersion is mandatory, and that the merged result is fully validated. The statement that 'a delta can never produce an invalid household' is a strong, non-obvious guarantee.

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 dense sentences pack the operation, scope, version requirement, and validation guarantee without filler. The core delta semantics are front-loaded, and the expectedVersion warning is placed immediately after the operation description.

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 with nested objects and no output schema, this description covers the operations, versioning prerequisite, and post-validation contract well. It does not mention error behavior on version mismatch or auth-related details, but the essential information needed to call the tool correctly is present.

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?

While the schema already describes set, remove, upsert, and api_key, the description reinforces the semantics and significantly clarifies expectedVersion by explaining why it is required and where to obtain it. It does not elaborate on id or api_key, but those are straightforward; overall it adds useful meaning beyond the schema.

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 uses a specific verb ('Apply a collection-level delta') and identifies the resource ('stored household') while enumerating the exact operations: set scalars, upsert entries, remove entries. It also differentiates itself from full-document replacement by stating 'without resending the whole document', which distinguishes it from the sibling replace_household.

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?

The description clearly states that expectedVersion comes from get_household and is REQUIRED, giving the agent a direct prerequisite and read-before-patch workflow. It does not explicitly name alternatives like replace_household for full replacement, so while context is strong, explicit when-not/alternative guidance is absent.

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