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

Annotations already include idempotentHint=true, but the description expands on this by detailing the case-insensitive match and that the existing label is returned unchanged. It also discloses that the new label is appended to the end of the display order. This adds meaningful behavioral context beyond the annotations, though it does not cover error scenarios or permissions.

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 sentences with no extraneous information. The primary purpose is stated first, followed by important idempotency and ordering details. The structure is efficient and front-loaded.

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 two-parameter create tool with annotations covering idempotency, the description provides sufficient context: what it does, the duplicate behavior, and ordering. It does not explicitly state the return value, but it is implied (the label or existing label). Given the simplicity, this is adequately complete.

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 50% (project_id has a description, name does not). The description does not add any parameter-specific details; 'by name' merely restates the parameter's existence. It fails to compensate for the missing description of name (e.g., constraints, format, case sensitivity), leaving the agent without clear parameter semantics.

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: 'Create a new label on a project by name.' The idempotency behavior is clearly described, and the tool is distinguishable from list_labels (which reads) and other create tools by its focus on label creation.

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?

Implied usage is to create a label, and the idempotency hint suggests it can be used safely without checking existence first. However, no explicit guidance is given about when to prefer this over alternatives like list_labels, and no exclusions or preconditions are stated.

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