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

Annotations already indicate this is a write operation (readOnlyHint=false) and not destructive. The description adds value by clarifying it's a partial update, that it returns the full updated object, and that space scoping behavior is involved. This goes beyond the annotations without contradicting them.

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 concise sentences, front-loaded with the main action and return value. Every sentence earns its place, and the space scoping guidance is packed efficiently.

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?

Given moderate complexity (nested body objects, no output schema), the description covers the core purpose, return behavior, and scoping, which is sufficient for invocation. It points to the OpenAPI spec for nested shapes, reducing the need to document every field.

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?

The description reinforces space_id override behavior already present in the schema, but adds no new meaning for the ad_group_id or body parameters. With 67% schema coverage, the description provides some extra context but doesn't fully compensate for undocumented parameters.

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 'Partial update of an ad group' with a specific verb and resource, distinguishing it from create_ad_group and other update tools. It also clarifies the return value ('Returns the full updated/created object'), making the purpose unambiguous.

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?

Explicitly mentions scoping to the active Space and gives two clear usage options: use set_active_space to switch or pass space_id to override for one call. It does not explicitly name alternative tools for creation/full updates, but the context is sufficient for correct use.

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