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

Annotations already declare this is a non-read-only, idempotent, non-destructive write, so the safety profile is covered. The description adds nothing beyond that: it does not explain the effect (that future sends to this address are blocked), whether the change is reversible, or any auth/rate considerations. With annotations carrying the safety load, the description is thin but not contradictory.

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 with zero waste. It is efficient, though arguably so terse that it omits useful context for a mutation tool.

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 return values need not be explained, and annotations cover the safety profile. However, for a write tool the description omits the operational consequence of suppression (blocking future sends) and the existence of the inverse operation, which an agent would benefit from knowing.

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 both parameters (email, reason) are already fully documented in the schema, including that reason is optional. The description adds no syntax, format, or semantics beyond the schema, 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?

The description states a specific verb (add) and resource (suppression list), and the name plus sibling set (list_suppressions, remove_suppression) makes the direction of the operation unambiguous. It does not explicitly name a sibling or contrast with alternatives, but the purpose is immediately clear.

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?

There is no guidance on when to use this tool versus remove_suppression or list_suppressions, no mention of prerequisites, and no indication of when suppression is appropriate (e.g., hard bounces, complaints, manual opt-out). The agent must infer all usage context.

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