Add list items

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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false and openWorldHint=true, covering the safety profile. The description contributes only that the target is a 'static list'; it says nothing about duplicate handling, partial success when some IDs fail resolution, or what happens if the list_id is invalid or not owned by the user.

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 with no filler, and the resource scope leads. It is appropriately sized for a simple append operation, though the terseness is part of why the guidance gaps exist.

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?

Incorrect resolution — see below.

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% – list_id, movies, shows and the imdb/tmdb identifier shapes are all documented in the schema with examples. The description only echoes the parameter names, adding no format or constraint information beyond that. 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?

States a specific verb and resource (add movies/shows) plus the target (one of the user's static lists), which cleanly separates it from remove_list_items and from add_watchlist_items. The word 'static' hints at the list-vs-watchlist distinction but the description never names the sibling it is not.

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?

No when-to-use guidance: it does not say how to obtain a valid list_id (get_user_lists / get_list) or when to prefer the watchlist variant. The only implicit cue is 'static lists,' leaving the agent to infer everything about prerequisites and alternatives.

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