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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the safe-append profile is known. The description adds the behavioral rule that duplicate same-day meals are permitted, but says nothing about what happens when the same recipe is added twice, whether existing plan entries are affected, or any limits — gaps that matter for an append mutation.

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 tight sentences, with the usage trigger front-loaded before the effect statement. No filler, no repetition of schema field names.

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 single-parameter tool with full schema coverage and annotations, this covers the essentials: what it does, when to call it, and the same-day multiplicity rule. It omits what the call returns or whether an updated plan comes back, which would matter since there is no output 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?

Schema description coverage is 100%, so date, mealType, recipeId, and servings semantics are already documented in the schema; baseline 3 applies. The description adds only the multiplicity note ('several meals on the same day'), which is largely a restatement of the array-of-meals shape.

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 states a specific verb and resource ('Adds one or more of the user's recipes to their Recipe One meal plan') and clarifies scope with 'several meals on the same day are allowed.' It implicitly distinguishes itself from remove_from_meal_plan and replace_meal_plan_entry via the additive verb, but never names a sibling to sharpen the boundary as a 5 would require.

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?

'Use this when the user wants to plan saved recipes for specific days' gives a clear, actionable trigger condition, and the saved-recipes qualifier excludes unsaved/imported dishes. There is no explicit when-not guidance or pointer to replace_meal_plan_entry for modifying an existing entry, so it stops short of a 5.

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