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

Annotations only show read-only=false and destructive=false, but the description adds meaningful behavioral detail: mail becomes a note, subject becomes the title, attachments carry over, an automatic 'email' tag is added, and the address is a secret anyone can write to. This goes well beyond the annotation hints.

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 front-loaded with the core action arborea, then presents behavior, parameters, and a safety warning in a compact logical order. No filler or repetition of the title beyond the first sentence.

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?

Covers purpose, parameter behavior, side effects, and a security warning for the user. It does not describe the exact response shape, but the instruction to 'tell the user the address once' implies the address is returned, which is sufficient for invocation.

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%, but the description adds extra meaning: null/omitted container_id routes to the Inbox, label forms the first part of the address, and tags are combined with an automatic email tag. These are not fully explicit in the schema descriptions.

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 and object—'Create an email capture address'—and immediately explains the core behavior: anything mailed to the address becomes a note in the chosen folder. It also flags the Pro-only restrictionhol and distinguishes this creation tool from the sibling email-addresses-list tool.

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 gives clear context for when to use the tool by explaining what it does, its Pro-only limitation, and the resulting side effect of incoming mail becoming notes. It does not explicitly contrast it with alternatives, but the creation purpose is unambiguous and the sibling list tool is not a plausible substitute.

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