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

Annotations already declare destructiveHint=true and idempotentHint=false, so the safety profile is covered structurally. The description earns credit by adding domain semantics the annotations cannot convey: the two suppression modes and exactly what traffic each blocks (campaigns, automations, unsubscribe_url sends). It omits reversibility and repeat-call behavior, which would have pushed it higher.

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 dense sentences with no filler; the default behavior and the contrast mode are front-loaded before the usage cue. Slightly packed with parenthetical asides, but each clause carries information.

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 destructive two-parameter mutation with no output schema, the description covers purpose, modes, and usage trigger adequately. Remaining gaps are the undefined bounce/complaint reasons and whether re-suppressing an existing address behaves idempotently.

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 0%, so the description must carry parameter meaning. It explains the `manual` default and the `unsubscribe` semantics well, but leaves the `bounce` and `complaint` enum values entirely undefined, so half the reason enum remains opaque.

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 ('Adds an address to the workspace's suppression list') and immediately distinguishes two operational modes (manual vs unsubscribe). An agent can tell this apart from siblings like add_subscriber or list_suppression 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?

Explicitly names the trigger condition: 'Use when someone requests no further contact outside the unsubscribe link.' That is a clear when-to-use signal, though it does not name a concrete alternative tool for in-scope unsubscribe cases, leaving that inference to the agent.

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