fastmail_create_masked_email

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

With no annotations provided, the description carries the full burden of behavioral disclosure, but it only states that a masked email is created. It does not mention side effects, permission requirements, uniqueness constraints, or what happens on duplicate creation. The word 'create' signals mutation, but little else is disclosed.

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 a single clear sentence with no redundant words. It front-loads the core action and resource, making it easy to scan and understand quickly.

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 mutating tool with no annotations and no output schema, the description is too sparse. It does not explain what happens after creation, whether creation is idempotent, what errors might arise, or what the agent should expect in the response. The schema covers parameters, but broader operational context 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?

Schema description coverage is 100%, so all three parameters are already documented in the input schema. The tool description adds no parameter-level meaning beyond what the schema provides, which is acceptable under the baseline, but it also does not compensate for any nuanced constraints.

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 uses a specific verb ('Create') and resource ('masked email address'), which clearly distinguishes this tool from its siblings like list, update, and delete masked email tools. It also adds the privacy-protection purpose, reinforcing the domain intent.

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 implies that the tool is for creating masked emails, but it provides no explicit guidance on when to use it versus alternatives, nor any conditions, prerequisites, or exclusions. An agent must infer usage solely from the tool name and sibling list.

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