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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the safety profile is known; the description goes beyond that by disclosing atomicity ("in a single transaction") and that the entryId and meal label survive the swap, which tells the agent the entry's identity and position are stable. It does not state what happens to the previous recipe assignment or how failures roll back, leaving some destructive semantics implicit.

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?

Three short sentences, front-loaded with the operation and its atomicity, then the preservation guarantee, then the input-provenance pointer. Nothing is redundant and no sentence could be dropped without losing information.

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 four flat parameters, full schema coverage, and annotations covering the destructive/safety profile, the definition supplies what an agent needs: provenance of identifiers, atomicity, and identity preservation. Only error/edge behavior (invalid or stale entryId) is unaddressed, a minor gap for a tool of this complexity.

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, entryId, recipeId, and the servings default are already documented in the schema, and the description's provenance note for date/entryId largely restates the schema wording. Baseline 3 is appropriate since the schema carries the parameter burden.

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?

"Replace one existing meal with another saved recipe" gives a specific verb (replace) and resource (a single planned meal entry), which is clearly distinguishable from add_to_meal_plan and remove_from_meal_plan by implication. It stops short of naming those siblings explicitly, so an agent must infer the boundary rather than read it.

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 the date and entryId returned by get_meal_plan" gives concrete pre-call guidance and routes the agent to the sibling that produces the required identifiers. There is no explicit when-not (e.g., use add_to_meal_plan when no entry exists yet), so the exclusion case is left to inference.

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