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

Annotations declare non-readOnly, non-idempotent, non-destructive, openWorld. The description adds behavior the annotations do not cover: the default is a dry-run preview and only confirm=true actually creates, plus the WEBPAGE variant returns tag snippets. It does not discuss permissions or how repeated calls behave, but the preview gate is valuable disclosure.

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 dense sentences with zero filler, front-loaded on the create action and its type distinction; the safety-relevant preview/confirm rule is placed last as the acting instruction.

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 9-parameter creation tool with no output schema and only 44% schema coverage, the description covers the important type and confirm semantics but leaves several fields (category, default_value_major, counting_type, primary_for_goal beyond 'primary by default') thin. Adequate but with clear gaps.

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 44%, so the description must compensate and only partly does: it explains type values, the confirm flag, and 'primary by default' (primary_for_goal), but category, default_value_major, and counting_type semantics are left to sparse schema text. Baseline is below 3 for this coverage level, and the description lifts it to a minimum-viable 3.

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 (create a conversion action) and enumerates the three supported types with concrete meaning for each (WEBPAGE form submit, WEBSITE_CALL site-swapped number, AD_CALL ad call asset). This lets an agent distinguish it from ads_update_conversion_action and ads_list_conversion_actions without opening schemas.

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?

Provides a clear operational rule ('Previews unless confirm is true') and notes the WEBPAGE variant returns installable tag snippets, which tells the agent when the tool is sufficient end-to-end. It does not, however, name an alternative path or state exclusions relative to the update/list siblings.

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