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

Annotations already declare destructiveHint=true, idempotentHint=true, readOnlyHint=false, so the safety profile is covered. The phrase 'provide at least one field' usefully implies partial-update semantics (omitted fields are left unchanged), but the description never explains what makes the operation destructive or which fields get overwritten.

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?

Two very short sentences, front-loaded, with no filler. However, the first sentence is pure redundancy with the tool name/title, so it does not fully earn its place.

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 annotations covering safety and a fully documented schema, most of what an agent needs is present. The gap is explanatory: nothing states that this is a partial update of an existing label, what happens to unspecified fields, or any permission requirement, which matters for a destructive mutation.

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 id, name, color (with enum), and description are all documented in the schema. The description only restates the 'at least one optional field' rule already implied by the required-only-id schema, adding no new semantics. Baseline 3 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?

The description repeats the tool title verbatim ('Update a label') and adds only an input constraint, not a functional statement. Unlike sibling update_* tools, it gives no hint of what a label update touches or how it differs from create_label/delete_label. This is a tautology restating the name.

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?

'Provide at least one field' is a validity constraint on the call, not guidance about when to use this tool versus alternatives like create_label or delete_label. There is no context, no prerequisites, and no exclusions.

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