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

The annotations already declare destructiveHint=true, so the agent knows this is a destructive operation. The description adds the context that it targets a 'library preference' and that 'kind' narrows the deletion, but it does not disclose side effects like irreversibility or behavior when the key doesn't exist. Since annotations cover the safety profile, the description adds modest value.

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?

The description is two sentences with no filler: the first states the action and parameters, the second gives the usage context. The key information is front-loaded, and every word contributes value. It is appropriately concise.

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 simple delete operation with two optional parameters and no output schema, the description covers purpose, parameters, and usage context. It omits details like error handling or idempotency, but given the tool's simplicity and the annotations covering destructiveness, it is sufficiently complete. A minor gap is the lack of explicit statement about the effects of an absent key, but this is not critical.

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 50% – only 'key' has a description. The description adds functional meaning to 'kind' by stating it 'narrows' the deletion, which is not in the schema. While it doesn't enumerate valid kind values, it provides the semantic role of the parameter, compensating partially for the missing schema description.

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?

The description clearly states the action ('Delete') and the resource ('saved library preference'), qualified by 'by key (optionally narrowed by kind)'. This distinguishes it from other delete tools like delete_label or delete_smart_view, which target different resources. The verb is explicit and the scope is well-defined.

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 provides a clear usage context: 'when the user changes their mind or asks you to drop something.' This tells the agent when to invoke the tool, but it does not explicitly state when not to use it or mention alternative delete operations for specific preference types. The guidance is clear but lacks exclusions.

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