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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is clear. The description adds value by explaining that the tool returns a facebook.com preview link and that it is for pre-activation review, which is useful behavioral context beyond the annotations. It doesn't mention any side effects, but the annotations cover the safety aspects.

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?

The description is two sentences with no wasted words. The core purpose is front-loaded, and the usage guidance is concise. Every sentence earns its place.

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 simple read-only tool with two well-documented parameters and no output schema, the description is complete. It explains what the tool does, when to use it, and what the output is (a preview link). The only minor gap is that it doesn't describe the format of the preview link or any potential failure modes, but these are not critical for a read-only preview tool.

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 100%, so the schema already documents both parameters. The description adds a small amount of context by noting ad_id comes from create_meta_ad_draft output, which helps the agent understand the parameter's origin. However, it doesn't add much beyond the schema, so the baseline 3 is appropriate.

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?

The description clearly states the tool's function: obtaining a facebook.com preview link for a drafted Meta ad. It specifies the resource (drafted Meta ad), the action (get a preview link), and the purpose (see what it looks like before activating). It also distinguishes itself from related ad tools like create_meta_ad_draft and set_meta_ad_status by focusing on the preview step.

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 description explicitly says to use this tool after create_meta_ad_draft or when the user asks to see a drafted ad. This provides clear when-to-use guidance and implicitly distinguishes it from activation tools like set_meta_ad_status. It could be slightly more explicit about when not to use it, but the stated usage context is strong.

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