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

Annotations already declare idempotentHint=true and destructiveHint=false, so safety is covered; the description adds genuinely useful context beyond that by naming the destination bucket and the three effects it explicitly will not trigger (follow, email, publish). It repeats the idempotency claim rather than adding new detail there, keeping it just under a 5.

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?

Three short sentences, front-loaded with the primary action and destination, followed by scope exclusions and idempotency. No filler; every clause carries information.

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 single-parameter, non-destructive mutation with full schema coverage and annotations covering safety, the description supplies everything needed: what it does, where the result lands, what it will not do, and retry safety. No output schema is required to fill gaps.

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% and the single 'list' parameter is documented as 'Exact list id or slug.' The description adds no syntax or format detail beyond the schema, so the baseline 3 for a fully-covered schema 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 (save), the resource (a live list), the destination (Library under Saved lists), and the scope (with its new picks). The negative clauses distinguish it from follow_curator, publish_list, and curator_notifications, so an agent can route correctly without opening a schema.

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 description clearly frames the context of use and explicitly rules out the side effects that sibling tools like follow_curator and publish_list perform. It stops short of naming an alternative to choose between (e.g., save_item vs save_list) or stating prerequisites, so it is clear context without explicit routing.

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