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

Far exceeds the annotations: discloses idempotency semantics (identical action set reuse, order-insensitive, reused=true), that an inactive goal yields warnings without auto-activation, the goal_name_taken error with the existing goal returned, that prior custom goals persist, and that use_account_default does not delete the custom goal. This is exactly the mutation-side-effect detail an agent needs for a destructiveHint=true tool.

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?

Dense but front-loaded: the scope constraint leads, then parameter semantics, then the idempotency/error decision tree. Slightly wall-of-text and partly in German while the tool names and annotations are English, which costs a little scannability.

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?

An output schema exists, so return values need not be explained, yet the description still names the reused/warnings/error fields the agent should inspect. Combined with the idempotency and reset semantics, nothing needed to call this destructive mutation safely 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 coverage is 0%, so the description carries the full burden and does: goal_name uniqueness scope and default template, workspace optionality when a single workspace exists, conversion_action_ids provenance and duplicate removal, and the override/ignore behavior of use_account_default. Every one of the five parameters gains meaning unavailable in the schema.

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 (set), resource (conversion goals / Custom Goal), and scope (only this campaign, other campaigns untouched) in the opening sentence. This clearly distinguishes it from ads_list_campaign_conversion_goals and ads_update_conversion_action, which operate differently.

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?

Points the agent to ads_list_conversion_actions as the source of IDs and to ads_list_campaign_conversion_goals for read-back, plus concrete recovery guidance for the goal_name_taken error. It does not explicitly contrast with a reset-vs-set alternative, though use_account_default covers the reset path within the same tool.

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