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

Annotations already cover safety (idempotent, non-destructive), but the description goes well beyond them: it explains that volume stays reduced while the rate is high and that a single additional bounce re-pauses the site. This post-call behavioral context is exactly what the schema and annotations cannot convey.

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?

Front-loaded with the action and condition, then the disambiguation from set_sending, then the behavioral caveat, then the caller instruction. Every sentence carries distinct, non-redundant information with no padding.

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 single-parameter action tool with no output schema, the description supplies the trigger condition, the alternative tool, side effects, and a pre-call obligation. Nothing an agent needs to invoke 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?

Only one parameter with 100% schema coverage, and the schema already explains workspaceId plus how to enumerate sites via get_status. The description adds no further parameter meaning, so the baseline 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 (restart sending) applied to a specific resource (a site that paused itself over bounce/complaint rate), and explicitly distinguishes itself from the sibling set_sending. An agent can tell exactly what this does and what it is not.

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 precise triggering condition (get_sending_health reports PAUSED automatically), names the alternative to use instead for the on/off switch (set_sending), and adds a caller obligation to explain the pause reason first. 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.