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

Annotations already flag destructiveHint=true and readOnlyHint=false, but the description adds the real behavioral payload: the scope of effect spans pending recipients in every campaign plus all future sends. It stops short of saying what happens on a duplicate address or whether the action is reversible, which matters given idempotentHint=false.

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?

Two tight sentences with the write tag and effect front-loaded; the second sentence carries non-redundant routing information. No filler.

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 single-parameter mutation with no output schema, the description covers the semantic consequence of the call well. Minor gaps remain around duplicate handling and error cases, but nothing an agent needs to select and invoke it correctly is missing.

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 0%, so the description must compensate. Saying it 'puts an address' on the list implies the single required parameter is an email address, but no format, single-vs-multiple, or validation detail is given beyond that inference.

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 ('Puts an address on the unsubscribe list') and immediately explains the effect (pending recipients skipped, future campaigns blocked). It doesn't name a sibling tool, but the closing line distinguishes it from removal, which is handled elsewhere.

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?

'Removing an address stays in the panel' implicitly rules out the inverse operation and signals there is no delete counterpart in this toolset. However, there is no explicit statement of when to choose this over list_email_unsubscribes or how it relates to add_email_list_members; the guidance is implied rather than stated.

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