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

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

Annotations indicate non-read-only, non-idempotent, and non-destructive, which the description aligns with. It goes beyond by disclosing that the response returns the entire favourites list, that AniList does not validate kind-id pairing, and that there is a confirmed read-after-write lag. No contradiction with annotations.

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?

The description is long but every sentence adds operational value: purpose, toggle behavior, response shape, id resolution, validation gap, and lag. It is front-loaded with the core purpose and follows with necessary caveats, with no filler.

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?

Given the tool's complexity, the description covers login requirement, exact toggle semantics, response list shape, parameter resolution process, a serious API validation gap, and a data consistency caveat. With an output schema present, this is fully complete.

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?

Although the schema already provides descriptions for both parameters, the description adds essential semantics: the id must be resolved from a tool matching the kind, and because AniList does not validate the match, incorrect pairings silently succeed. This is critical usage knowledge not present in the schema.

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 uses the specific verb 'toggle' and clearly identifies the resource: an anime, manga, character, staff member, or studio in the authenticated user's AniList favourites. It distinguishes this from sibling tools by focusing on the favourites toggle action, not list entries or user follows.

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?

Provides explicit workflow: resolve the id via search_media/get_media, search_character/get_character, etc., based on kind. It also warns against reusing IDs and explains the toggle behavior (calling again un-favourites). The read-after-write lag note gives additional guidance for verification.

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