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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered structurally. The description adds only the useful scope detail that both addresses and domains are returned, with no pagination, ordering, or count information.

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 short fragment with zero filler; the resource is front-loaded immediately. It is efficient, though its brevity is partly under-specification rather than deliberate density.

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 low-complexity, zero-parameter read with rich annotations, the description covers what is listed and whose list it is. It stops short of describing the return shape (no output schema exists) or whether the list is paginated, which an agent may still want.

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 tool takes zero parameters, so there is nothing for the description to clarify beyond what the (empty) schema shows. Baseline 4 applies for a parameterless tool.

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 is a noun phrase naming the resource ('blocked addresses and domains') and its scope ('the account's'), which is slightly more than the title's 'List blocked addresses' because it adds domains. However, it states no verb and does not distinguish itself from siblings such as block/unblock beyond the resource name, leaving purpose only implied.

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 when-to-use guidance, no mention of prerequisites, and no reference to the obvious alternatives (block to add, unblock to remove, or add_unsubscribe for a related list). The agent must infer that this is the read side of the block/unblock pair.

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