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

Annotations already declare destructiveHint=false, idempotentHint=true and readOnlyHint=false, so the safety profile is covered. The description adds genuine behavioral detail beyond that: restoration puts the message back into conversation and search results and preserves its labels, which tells the agent about side effects not visible in the annotations.

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 front-loaded sentence that states the action, the source, the destination, and preserved state 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 annotations covering safety/idempotency and an output schema present, the description is nearly complete for a one-parameter tool. Minor gaps remain: it does not say what happens if the message is no longer in Trash or whether restoring an already-inbox message is a no-op.

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% and message_id is fully documented (format, pattern, and provenance from list_trash), so the schema carries the parameter burden. The description adds no parameter-level detail, which is the expected baseline of 3 when the schema is complete.

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?

Specific verb (restore) + resource (received email) + source and destination (from Trash to inbox), and 'received' explicitly distinguishes it from the sibling restore_sent_message. An agent can pick this apart from its siblings without opening the schema.

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 phrase 'from Trash' implies the precondition that the message must currently be in Trash, but there is no explicit when-to-use guidance, no statement of when not to use it, and no named alternative such as restore_sent_message for the sent-mail case.

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