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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so safety is covered. The description adds substantial domain behavior beyond that: the three scope values and precisely which sends each one blocks, which is not derivable from annotations or the schema enum-less array.

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 sentences, front-loaded with the core action and the marketing/API-platform boundary before the scope semantics. The final sentence is dense and repeats the 'scope' framing twice, but nearly every clause earns its place given the ambiguity of the domain.

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 no-required-parameter list tool with no output schema, the description covers the main conceptual trap (marketing scope vs Marketing Platform campaigns) and notes that entries carry their scope. It stops short of describing pagination defaults or the overall response shape, but leaves nothing misleading.

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 page, limit, reason, search, date_from/date_to and sort_order are already documented at the field level. The description restates the same filter axes and adds only the meaning of the scope values, which is modest added value over the schema baseline of 3.

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 opens with a specific verb and resource ('List suppressed recipients') and immediately bounds it to the API Platform (Email API / SMTP) suppression list, explicitly excluding Marketing Platform campaigns. An agent can tell this is a read/list tool for API-Platform suppressions without inspecting 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?

It gives clear context for when this list is the right source (API Platform sends) and an explicit exclusion ('does not apply to Marketing Platform campaigns'), plus the available filter axes. It does not, however, route the agent to siblings like add_suppressions or reactivate_suppression for the write-side operations.

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