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

Annotations declare a non-destructive write, and the description adds real context beyond them: the key comes from the server environment and is never an argument, the scope is inventory:write, and unapproved accounts are rejected by the backend. The return shape (unit id and container root) is also disclosed, though no failure modes beyond approval are described.

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 tight sentences, front-loaded with the action and then the auth and approval prerequisites, then the return value. Dense but every sentence carries distinct information; no padding or repetition of the title.

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 mutating tool with no output schema, the description covers the three things an agent would otherwise lack: the auth mechanism and where the credential comes from, the account-level gate that causes failure, and what the call returns.

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 86%, so the schema already carries most parameter meaning, establishing a baseline of 3. The description adds nothing about individual parameters — it does not clarify the type enum tradeoffs or how size interacts with interstitial types, which the schema only hints at.

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 and resource ("Create a Sulvo ad unit") plus a precondition (approved publisher), which is more specificity than a bare name restatement. It does not, however, distinguish itself from near siblings like create_sulvo_auto_sticky_units or create_sulvo_interstitial_units, which create ad units in bulk or by category.

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?

Gives a clear precondition (account must be approved, key must be write-scoped) that guides whether a call can succeed at all. It offers no exclusion or alternative-selection guidance — an agent cannot tell from this text when to pick this single-unit tool over the other ad-unit creation siblings.

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