save_to_library

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

No annotations are provided, so the description carries the full burden. It does disclose a genuinely useful behavioral trait beyond the schema: auto-chunking at 40 URIs per request. However, it says nothing about required OAuth scopes, whether saving is idempotent, or side effects of following endpoints — gaps for an unannotated mutation tool.

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 action, then the chunking constraint, then parameter detail. Every sentence carries information; the Args block is somewhat redundant with the schema but still short and readable.

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?

An output schema exists, so return values need no explanation. But for an unannotated mutation tool with 0% schema coverage, the description omits auth requirements, error behavior, and idempotency — the auto-chunking note is the only behavioral detail. Adequate but not 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?

Schema description coverage is 0%, so the description must compensate and it largely does: it enumerates every accepted URI type (track, album, episode, show, audiobook, artist, user, playlist) and gives concrete examples. It could still note format expectations more assertively, but the added meaning over the bare 'array of strings' schema is substantial.

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?

Specific verb+resource: saving items to the user's library and following artists/users/playlists. It covers both behaviors clearly, though it does not explicitly distinguish itself from siblings like remove_from_library or check_saved_in_library beyond the obvious verb difference.

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?

Usage is implied by the verb 'save' and the URI-type list, but there is no explicit when-to-use or when-not-to-use guidance relative to the many siblings (remove_from_library, add_playlist_items, check_saved_in_library). An agent can infer intent but gets no routing help.

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