fastmail_update_masked_email

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

There are no annotations, so the description carries the behavioral disclosure burden. It discloses that the tool mutates the masked email's state or description, which is valuable, but it does not explain side effects, permissions, reversibility, or the meaning/impact of the 'pending' state seen in the schema.

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, front-loaded sentence with no filler. Every word earns its place by communicating the resource and the specific update operations.

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?

The tool is simple, the schema covers all parameters, and sibling tools provide surrounding context. However, with no annotations and no output schema, the description omits behavioral details like what a successful update returns, whether enabling/disabling has immediate effects, and what 'pending' implies—useful context for an agent invoking this tool.

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 the schema already documents all three parameters. The description adds no parameter-specific meaning beyond confirming that enable/disable relate to state and description can be changed, which aligns with but does not enhance the schema.

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 ('Update') and a clear resource ('a masked email'), and immediately enumerates the three actions it supports: enable, disable, or change description. This distinguishes it from sibling tools like create/delete/list masked emails without requiring schema inspection.

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 clearly communicates that the tool is for modifying an existing masked email, which is distinct from creating, deleting, or listing them. It does not explicitly say when not to use it or name alternatives, but the context is clear enough from the action and sibling names.

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