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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=true. The description adds real value beyond them: dry-run behavior ('Previews unless confirm is true') and the fact that WEBPAGE returns tag snippets to install. Permissions/auth requirements are not covered, keeping it from a 5.

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?

Three compact sentences, front-loaded with the verb and resource, then the variant list, then behavioral notes. No filler or repetition.

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 create tool with no output schema, the definition covers the mutation semantics, the dry-run gate, and even hints at output (tag snippets for WEBPAGE). Missing detail on account scoping (customer_id) and default values for secondary parameters keeps it just short of complete.

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 56%, so the schema documents some fields but not all. The description supplies the meaning of the otherwise-undocumented 'type' enum values and clarifies the semantics of primary_for_goal ('Primary by default') and confirm (preview gating). Several parameters (category, counting_type, default_value_major, phone_call_duration_seconds) rely on the schema alone.

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 (Create) and resource (conversion action), then distinguishes the three variants (WEBPAGE, WEBSITE_CALL, AD_CALL) with concrete descriptions of each. This clearly separates it from siblings like ads_update_conversion_action and ads_list_conversion_actions.

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 type explanations give implied guidance on which variant to pick, and the preview/confirm note is useful context. However, it never states when to reach for this tool versus ads_update_conversion_action or ads_list_conversion_actions, so tool-level selection is left to inference.

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