Favourite/unfavourite an anime, manga, character, staff member, or studio

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

Discloses that it toggles (mutates) the favourite state and requires authentication. Annotations provide no destructive hints, but description adds toggle behavior and login requirement, beyond what structured fields convey.

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 sentences, no wasted words, front-loaded with purpose and key constraints. Highly efficient.

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 toggle tool with output schema (return values presumably documented there), description covers prerequisites, ID resolution, and toggle behavior. Complete enough.

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 covers both parameters with descriptions, but the description adds critical context: id must be resolved via other tools matching the kind, which is not in schema. Thus adds significant meaning.

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 clearly states the tool toggles an entity in the authenticated user's favourites, with a specific verb 'Toggle' and lists all five entity types, distinct from sibling tools.

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 requires login, explains toggle behavior (calling again un-favourites), and instructs to resolve IDs via specific search tools matching the kind. Lacks explicit when-not-to-use but adequately covers context.

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