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

Annotations already declare destructiveHint=true, idempotentHint=true, and readOnlyHint=false. The description adds useful behavioral context by stating this is a WRITE operation and that reversal requires the subscriber to opt in again.

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?

Front-loaded with 'WRITE' and the core effect, then adds the reversal caveat and endpoint. It is brief and every sentence provides useful 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 simple one-parameter unsubscribe tool, the description plus annotations cover the key behavior. It does not describe response or error behavior, but no output schema exists and the core action is clear.

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 coverage is 100%, and the single required email parameter is fully documented in the schema. The description does not add further meaning about parameter usage, so baseline 3 is appropriate.

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: unsubscribe a subscriber from campaigns. It clearly distinguishes from siblings like add_subscriber, update_subscriber, and get_subscriber.

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?

Clearly indicates the action is for unsubscribing a subscriber so they stop receiving campaigns. It notes reversal requires the subscriber to opt in again, but does not explicitly contrast with alternatives such as update_subscriber.

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