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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety and repeatability profile is fully covered upstream. The description's added value is the framing that favorite=false 'takes the mark away' rather than deleting anything, which correctly signals a reversible toggle. Beyond that it says nothing about error behavior on an unmatched title or whether the member favourite overrides a family favourite.

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?

A single front-loaded sentence covering the action, the boolean direction, the scope options, and the title source requirement. No redundant or filler wording.

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 three-parameter boolean toggle with full schema coverage and complete annotations and no output schema, the description supplies everything needed to call it. The only gaps are edge-case handling (unknown title, member vs. family precedence), which are minor for this tool's 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 all three parameters are already documented, and the description's statements about favorite and the exact recipe title restate the schema. It adds no extra semantics for memberName precedence or title matching rules, 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?

The description names a specific verb and resource ('Mark a recipe as a favourite') plus the scope variants (family vs. one member), which separates it from sibling tools like add_food_preference or wish_dish. It never names a sibling alternative, but the recipe-favourite domain is distinctive enough that differentiation is largely implicit.

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?

It gives actionable preconditions ('Use the exact title from get_recipes') and explains the boolean direction plus the memberName default. It stops short of exclusions — e.g. whether this replaces or coexists with food preferences, or what happens if the title is not found — so it is clear context rather than full when/when-not guidance.

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