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

Annotations already cover the safety profile (readOnly=false, idempotent=true, destructive=false), so the bar is lower. The description adds real context beyond them: sync timing ('from the next sync'), the 30-day backfill window, that new-lead discovery is off by default, and that re-adding a stopped mailbox resumes rather than errors.

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 action is front-loaded and each sentence adds a distinct fact (prerequisite, sync/backfill, alternative, default, resume). The prose is somewhat flowery and dense ('its letters join the leads' timelines'), but nothing is redundant.

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 one-parameter, non-destructive mutation with no output schema, the description covers prerequisites, side effects, defaults, the alternative tool, and re-add semantics. Nothing an agent needs to call it correctly is missing.

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% for the single 'address' parameter, so the schema already carries the meaning. The description adds no format or syntax detail beyond the schema's own example, so the baseline of 3 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 (add) and resource (a mailbox of the company's Google Workspace) plus the scope it joins (what this workspace reads). It explicitly distinguishes itself from the sibling link_to_connect_your_mailbox, so an agent can route correctly 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?

Gives the prerequisite (Workspace admin has granted domain-wide delegation) and names the alternative path (a person connecting their own mailbox via sign-in with link_to_connect_your_mailbox). When-to-use and when-not are both explicit.

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