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

With no annotations, the description carries the full burden. It adds real value by disclosing that the campaign is paused first and spend stops on the first call, which is non-obvious sequencing behavior. It does not disclose whether the stop is reversible, whether the plan can be relaunched with launch_ad_plan, what state the plan ends in, or what the response returns.

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 short sentences with no filler, and the key operational fact (spend stops immediately) is front-loaded after the action statement. Slightly terse given the remaining gaps, but structurally sound.

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 mutation tool with no annotations, no output schema, and an undocumented agent_id, the description covers the spend-stopping behavior but leaves reversibility, resulting state, and the meaning of agent_id to inference. Adequate minimum but clearly 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 only 50%: plan_id is documented as coming from list_ad_plans, but agent_id has no description anywhere. The description text adds no parameter meaning at all, so it fails to compensate for the undocumented required parameter.

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+resource: switching one launched ad off, which maps to stop_ad_plan and is clearly distinct from launch_ad_plan in the sibling list. The wording 'launched ad' rather than 'ad plan' is slightly loose but an agent can identify the operation.

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 phrase 'one launched ad' implies a precondition (the plan must already be launched), which usefully distinguishes this from launch_ad_plan. However, there is no explicit when-to-use/when-not guidance and no mention of what to do if the plan is not launched.

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