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

Annotations already declare non-destructive and idempotent behavior, so the safety profile is covered. The description adds a genuine prerequisite ("authenticated native buyer and existing funded placement") that is not in the annotations or schema. It stops short of describing side effects or what the created experiment represents, so the added context is useful but thin.

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 core purpose plus prerequisite are front-loaded. It is efficient, though it trades thoroughness for brevity given the tool's mutation semantics.

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?

With annotations covering safety and full schema coverage on parameters, the description supplies the missing prerequisite context. With no output schema, it could say more about what is returned or the experiment lifecycle, but the essential calling information is present.

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 all six parameters, including the objective enum values and the idempotency_key semantics. The description adds no parameter-level meaning beyond that, so the baseline 3 applies.

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 ("Create an experiment") scoped to "a funded native media-buy placement," which distinguishes it from the generic create_experiment and from create_media_buy/create_campaign. It does not explicitly name the create_experiment sibling, but the native/funded scope makes the domain clear.

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?

"Uses your authenticated native buyer and existing funded placement" establishes prerequisites, implying you should call this only when a funded native placement already exists. However, it never says when to prefer this over create_experiment or create_campaign, nor what happens if the placement is missing; usage is implied rather than explicit.

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