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

Annotations already declare readOnly, idempotent, non-destructive, so the safety profile is covered. The description adds genuinely non-obvious behavior beyond that: emails are withheld by default and replaced by domain, and there is a stated consent condition for revealing addresses. Good added context, though nothing about pagination or limits on large result sets.

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 purpose sentence followed by the privacy rule, then compact Args and Returns sections. Every element is doing work given the empty schema descriptions, though the Args list partly restates parameter names the schema already carries.

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?

With no output schema, the inline Returns block (total, count, items with their fields) is a meaningful addition. Combined with the email-privacy rule, an agent has enough to call and interpret this tool; only response_format behavior and any pagination/numbering limits go unaddressed.

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 carries the full burden — and it documents ideaId, runId, and includeEmails including its default of false, which is not in the schema. It omits response_format, one of the four parameters, so it does not fully compensate for the coverage gap.

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?

Specific verb (List) plus resource (signups for an idea) with an explicit scoping qualifier ('optionally narrowed to one Ad Run'). An agent can distinguish it from sibling tools like idealaunch_get_idea or idealaunch_list_ad_runs without opening 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?

Tells the agent when to use runId (only signups attributed to that Ad Run) and gives a real conditional rule for includeEmails ('do that only when the founder has asked for them'). No sibling tool lists signups, so there is no alternative to disambiguate against — clear context but no explicit exclusions.

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