Create email forwarder

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

Beyond the annotations (which only declare readOnly=false, idempotent=false, destructive=false, openWorld=true), the description discloses substantive behavior: `:blackhole:` silently discards mail, `:fail:` rejects it, and forwarding to Yahoo/AOL/Gmail automatically enables Expert Spam Filtering for the domain. These non-obvious side effects and special-value semantics are exactly what an agent cannot learn from annotations or 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?

A single dense sentence, front-loaded with the core action, followed by the special-value semantics and the side effect. Every clause carries information, though the semicolon-heavy packing makes it slightly harder to scan than two or three shorter sentences.

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 3-required-param creation tool with no output schema, the description covers the action, the special destinations, and a notable side effect. It omits return/failure behavior (e.g., what happens if the alias already exists), which is a minor gap given the annotation set already flags non-idempotence.

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%, so the baseline is 3, but the description adds real meaning: it shows how `alias` and `domain` combine into `alias@domain`, and explains what the `:blackhole:` and `:fail:` destination values actually do, which the schema only lists by name.

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 names a specific verb (creates), the exact resource (`alias@domain` forwarder), and the destinations it routes mail to. It is immediately distinguishable from siblings like create_email_account or create_domain_pointer.

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?

It provides one procedural caution (confirm with the user before using `:blackhole:`) but never states when to choose this tool over alternatives such as create_email_account or set_catch_all, nor any precondition beyond the confirm step. Usage is implied rather than explicitly scoped.

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