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

Annotations already declare destructiveHint=true, readOnlyHint=false and idempotentHint=true, so the safety profile is covered. The description still adds real value beyond that: it specifies that underlying sources are preserved (only the grouping is removed), that the operation is irreversible, and even the return shape ('label id with deleted: true') and route. This is above the annotation baseline, though 'cannot be undone' largely restates destructiveHint.

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 tight sentences, front-loaded with the effect and the preservation guarantee, then alternatives, then return value and route. Every clause earns its place and nothing is filler.

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?

No output schema exists, but the description discloses the return ('label id with deleted: true') and the API route. For a single-parameter destructive delete whose annotations cover safety, nothing an agent needs to call it correctly 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?

One parameter with 100% schema description coverage; the schema already documents 'label' as 'Label id, from notebook_list_labels'. The description adds no format, example, or constraint details beyond what the schema provides, so the baseline of 3 is appropriate.

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+resource and scope: 'Permanently delete one source label from its notebook'. It immediately clarifies what is and isn't affected ('the sources under it stay in the notebook, only the grouping goes') and names the siblings it differs from, so an agent can distinguish it from notebook_update_label and notebook_create_labels without reading further.

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?

Explicitly routes the agent: use notebook_update_label to rename the label or move sources off it, and notebook_create_labels with auto: all to relabel every source at once. Conditions and alternatives are stated, not implied.

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