create_list_item

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

Annotations already declare the write/non-idempotent/non-destructive profile, so the description's job is smaller. It adds genuinely useful behavior: the fallback to the default grocery list when no list is given, and that the call returns a confirmation of the added item. Duplicate handling is only implied by idempotentHint=false rather than stated.

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-loads the purpose, then usage cases, then parameters, then return and related tool — a clean, scannable structure. Mild redundancy in re-listing parameters that the schema already describes, but nothing is verbose.

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 no output schema, the description correctly states the return ('confirmation of the added item') and points to get_lists for discovering list IDs, covering the main preconditions. The one gap is what happens if both listId and listName are provided, leaving a real calling decision unresolved.

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 coverage is 100%, so all four parameters are already documented in the schema; the description's parameter list largely restates those field descriptions. It does not resolve the meaningful ambiguity of precedence when both listId and listName are supplied, which would be value beyond 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?

Opens with a specific verb and resource ('Add an item to a Skylight list') and reinforces it with concrete example phrasings for grocery and to-do items. It does not explicitly contrast with the nearest siblings (update_list_item, create_list), so an agent must infer the boundary, but the core action is unambiguous.

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?

The 'Use this when' block gives three concrete invocation scenarios spanning grocery, to-do, and generic lists, plus the default-list fallback. It stops short of stating when NOT to use it (e.g., editing an existing item belongs to update_list_item) and does not name that alternative.

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