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

Annotations already declare non-read-only, idempotent and non-destructive, so the description earns credit for what they don't say: omitted fields are preserved, supplied lists replace wholesale, the call returns the saved preferences, and the change propagates to the next planning/search/recipe call on every surface. The linked-account prerequisite and the explicit 'not built for managing allergies' limitation are exactly the behavioral context annotations cannot carry.

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 verb and fields, then the mutation semantics, then downstream effects and prerequisites — a sensible ordering. A few clauses are dense, notably the long allergy disclaimer sentence, but each still carries decision-relevant information for an agent deciding whether it may claim allergy safety.

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 needn't detail return shapes, and it covers everything else an agent needs: all parameters optional, replacement semantics, the required linked account, and the downstream scope of the change. Nothing material is missing for correct invocation.

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?

Schema description coverage is 100%, and the schema already documents each parameter's omit-to-keep and empty-list-to-clear semantics plus the enum of 14 avoidable foods. The description restates the whole-list replacement rule but adds no syntax or format detail beyond what the schema provides, so the baseline 3 applies.

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 ('Changes the account's food preferences') and immediately enumerates the exact fields affected: diet, foods to avoid, dislikes. The reference to get_food_preferences makes the read/write split with its closest sibling unambiguous.

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?

Explicitly routes the agent to get_food_preferences to obtain the current value before a partial change, and states the replace-whole-list rule so the agent knows how to express a single-item edit. It does not state a 'do not use for X' exclusion beyond the allergy caveat, so it stops short of a full 5.

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