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

Annotations already declare this is a non-read-only, destructive-flagged, closed-world write. The description adds real context beyond that: the account-placement rule, the case-insensitive duplicate-name failure mode, and the fact that the new list's id is returned. It stops short of describing permissions or what state exists after a failed call.

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?

Four tight sentences, front-loaded with the core action and account scope, then the failure condition, return value, and next step. No filler and nothing repeated from the schema.

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?

For a two-parameter creation tool with an output schema, this covers the essentials: where the object lands, what breaks it, what comes back, and what to call next. Nothing an agent needs before invoking it is missing.

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%, including the note that `confirm` is ignored, so the schema already carries parameter semantics. The description adds only indirect meaning by explaining there is no account parameter to choose. Baseline 3 applies when the schema does the heavy lifting.

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 ("Creates a new list in Apple Reminders") and pins the scope ("in the same account as the default Reminders list"). It is clearly separable from create_reminder, which it explicitly names as the tool for adding items to the list.

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?

Gives clear routing advice: use create_reminder with this list name to populate it, and warns that a duplicate name (case-insensitive) causes failure. It does not point at get_reminder_folders/list_reminders as a pre-check to avoid that failure, so the when-not guidance is implied rather than complete.

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