Create label

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

Annotations only cover the safety profile (readOnlyHint=false, destructiveHint=false). The description adds real behavioral context beyond that: ProtonMail stores it as a folder under Labels/, and for standard IMAP keywords the call is a no-op because labels are auto-created on first use — a critical 'this may do nothing' disclosure.

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 then the backend-specific behavior. Every sentence carries information; nothing is redundant with the title.

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 creation tool with no output schema, the description covers the key ambiguity (per-backend behavior and the no-op case). It lacks only sibling routing guidance to be fully 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 coverage is 100%, and the schema itself documents both parameters including the '/' nesting convention and the list_accounts reference. The description adds no parameter-level meaning, so the baseline of 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?

States a specific verb and resource ('Create a new label') and goes further by distinguishing the two backends it can act on. It does not, however, explicitly contrast itself with the sibling 'add_label' (apply) vs 'create_label' (define), so an agent must infer that boundary.

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?

Usage is implied rather than stated. The No-op caveat for standard IMAP keywords hints at when this call is pointless, but there is no explicit guidance like 'use add_label to apply an existing label to a message' or prerequisites beyond the account param.

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