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

Annotations already declare destructiveHint=true and idempotentHint=false, but the description adds the key consequence the annotation cannot express: the old address stops working, i.e. the change is externally irreversible for senders. It also discloses the confirmation requirement. It stops short of stating whether the old address is recoverable from any history.

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, front-loaded sentences: what happens, the failure mode that motivates it, and the safety protocol. Every sentence earns its place with zero filler.

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?

With one fully documented parameter, annotations covering the safety profile, and an output schema to describe the return, the description supplies exactly the missing pieces (random replacement, old address invalidation, user confirmation). Nothing an agent needs before calling is absent.

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?

There is a single parameter with 100% schema description coverage ('The sheet whose inbound address is replaced'), so the schema already carries the meaning. The description only implies sheet scoping and adds no format or identifier guidance beyond it – the baseline 3 for full coverage 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 ('Replace a sheet's inbound email address') plus the outcome ('with a new random one'), which distinguishes it semantically from inbound_email.rename even though that sibling is never named. Clear and specific, but no explicit sibling differentiation.

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?

Gives a concrete trigger condition ('when the old one gets spam') and adds a human-in-the-loop rule ('Always asks the user first'), which tells the agent the workflow context. It does not, however, contrast this with inbound_email.rename or state any exclusions.

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