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

Annotations already declare readOnlyHint=false, destructiveHint=false, and idempotentHint=true, covering the basic safety profile. The description adds 'Old style' (legacy connotation) and the email requirement, but does not explain side effects (e.g., confirmation, list size) or what happens on success. It does not contradict annotations, and given the annotations, the added value is moderate.

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?

The description is brief and front-loaded with the core purpose. The 'Prefer want...' guidance is concise and useful, though the informal tone and 'Old style' label add slight ambiguity. It earns points for efficiency.

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 tool with 4 params and no output schema, the description covers the essential action and usage. However, it conflicts with the schema by stating email is needed when the schema marks it optional, and it omits any explanation of the 'referral' parameter. Given the low complexity and annotations, this is slightly incomplete.

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%, so all parameters are documented. The description highlights email as needed and names 'want' and 'platform' as optional, but does not mention 'referral'. This adds minimal value beyond the schema, so a 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?

The description clearly states the action: putting the human on a list to hear about a product launch. It also differentiates itself from siblings by labeling itself 'Old style' and directing to prefer 'want' or 'hold', giving context on its role. However, the phrasing is informal and slightly ambiguous (e.g., 'next product'), which prevents a 5.

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?

The description explicitly advises when not to use this tool: 'Prefer want with a link, or hold on what's live.' It also states a prerequisite ('Needs their email') and optional inputs. This gives clear routing guidance against siblings, exceeding the typical standard.

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