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

Annotations already establish this is a safe, idempotent read. The description adds genuine context beyond them: that include_email requires write access and that the tool reports archive/delete eligibility. It stops short of describing rate limits or pagination, but those are low-relevance for a single-resource getter.

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?

Two tightly packed sentences with the return scope front-loaded and the routing guidance trailing. Every clause carries information; nothing is 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?

An output schema exists, so the description need not detail return values, and it still summarises the useful ones. For a read tool with full annotation and schema coverage this is sufficient, with only minor behavioral detail omitted.

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 baseline is 3. The description's claim that include_email=true exposes address and receiving state largely restates the schema's own note that it requires upload/write access and returns receiving/sending state, adding little that is not already structured.

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 (Get) and resource (mailbox) and enumerates exactly what is returned: details, current revision, email activity, and archive/delete eligibility. It also names the sibling tools that cover adjacent resources, so an agent can distinguish it without opening a 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?

Explicitly routes the agent to alternatives with conditions: mailbox_file_list for files, mailbox_email_list for messages, account_limits for quotas. It also flags the write-access prerequisite for include_email, leaving little to inference.

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