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

Annotations declare a non-destructive write (readOnlyHint false, destructiveHint false), and the description adds two traits beyond them: the new ad group defaults to PAUSED, and Amazon will reject mixed targeting with an otherError. It does not cover the confirm_id preview-then-write flow in prose, but the schema documents that token.

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?

Front-loads the core action and default state, then the critical constraint. The bulk of the payload is a dense but earned domain warning; the only real structural cost is the mid-description language switch to Italian, which is jarring in an otherwise English toolset.

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 output schema and a private (openWorldHint false) backend, the description covers the default state, the key failure mode, and the correct workaround involving two sibling create tools. It omits sequencing with ads_create_sp_campaign, but the essential call-time context 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 67% and the required nested fields (name, campaign_id, default_bid) are self-evident from the schema. The description's targeting-type rule is behavioural rather than parameter-level, so it adds little parameter meaning beyond what the schema already carries.

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 SP ad group) and scopes it to an existing campaign, which cleanly separates it from the ads_update_sp_ad_group and ads_list_sp_ad_groups siblings. An agent knows exactly what this produces without opening the schema.

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 unusually specific domain guidance: an ad group must be keyword-targeted OR product-targeted, never both, and it routes the agent to ads_create_sp_keywords and ads_create_sp_product_targets for the two separate ad groups. It stops short of stating prerequisites such as creating the campaign first or previewing via confirm_id, but the when-to-use routing is strong.

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