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

Annotations already establish read-only and open-world behavior, so the bar is lower. The description still adds real value beyond them by disclosing the extra fetch cost of mal=true, that the enrichment is scraped credential-free from the public MAL page, and that the mal block is omitted when the title has no MAL id.

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?

Front-loaded with the core purpose, then the optional enrichment, then the sibling routing. The long enumerated field list is informative but borders on cataloging what the output schema already carries, and 'credential-free' is stated twice.

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 an output schema present, return values need not be re-explained, and both parameters plus the enrichment behavior are covered. The only residual gap is the anime-vs-manga wording around the id parameter, which could confuse an agent about whether an anime id is acceptable.

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 both id and mal are already documented in the schema, and the description largely restates the mal behavior rather than extending it. Note a minor tension: the schema describes id as an 'AniList anime id' while the description frames the tool as manga, which slightly muddies the identifier semantics.

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?

States a specific verb and resource ('Returns a normalized manga by AniList id') and enumerates the substantive fields returned, so the agent knows this is a full-record lookup rather than a list. It also explicitly disambiguates from manga_search.

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 routes search intent elsewhere ('Use manga_search to search manga'), giving the agent a clear alternative. It stops short of stating prerequisites or when-not conditions (e.g. that a pre-existing AniList id is required input), so it is clear but not exhaustive.

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