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

Beyond the annotations, the description discloses the auth tier (`full_access` key), the fixed reason value applied, the endpoint/operationId, and the dedupe behavior of re-adding an existing address. One nuance worth noting: annotations declare `idempotentHint: false`, yet the stated 'returns the existing entry' behavior implies repeated calls have no additional effect — an agent doing retry logic could be misled, but this is a hint-level tension rather than a direct safety contradiction.

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?

Three short, front-loaded lines with no filler; the only redundancy is restating 'Add a suppression' from the title before the substantive detail.

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 create tool with no output schema, this covers the essentials: auth requirement, side-effect semantics, and idempotent-ish re-add behavior. Minor omissions are what 'reason `manual`' implies (other reasons exist but are not settable here) and the downstream effect of suppressing an address.

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?

The schema is present but has 0% description coverage for the single `email` parameter. The description only refers to "the address", adding no normalization rules, case handling, or validation detail beyond the schema's `format: email`.

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 and resource ("Add a suppression") and clarifies what it actually writes (the address with reason `manual`). It is distinguishable from delete_suppression and list_suppressions by name alone, though it never explicitly names those siblings.

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?

It gives the prerequisite (a `full_access` API key) and the re-add behavior, which helps an agent decide to call it safely, but it never states when to use this versus delete_suppression/list_suppressions or what business situation warrants suppressing an address.

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