google_ads_ad_groups_update

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

With no annotations, the description fully discloses the tool's behavioral traits: mutating, not automatically reversible, returns updated ad group, and does not cascade. It also provides a mitigation for rollback via mureo_state_action_log_append. This goes well beyond basic expectations for an update tool.

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 sentences, each with clear purpose: action+partial update, return value+rollback advice, non-cascade guidance. No redundancy or filler. The information is front-loaded with the primary purpose then important caveats.

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 no output schema, the description notes 'Returns the updated ad group,' covering the return value. It also addresses related tools and rollback. It does not mention permission requirements or error conditions, but for an update tool with these details, it is largely complete.

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 coverage is 100%, so each parameter already has detailed descriptions. The tool description adds semantic context about how parameters are applied (partial update, only provided fields changed), which clarifies parameter behavior globally. It could add more per-parameter details, but the schema handles the heavy lifting.

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 action: 'Updates one or more settings on an existing ad group.' It specifies the resource (ad group) and the verb (updates), and differentiates from create/list by focusing on existing ad groups and partial updates. It also distinguishes from related tools by noting it does not cascade to ads or keywords.

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?

Provides explicit usage guidance: 'Partial update — only provided fields are changed' clarifies when to use this tool for targeted modifications. It also gives clear exclusions and alternatives: 'Does not cascade to ads or keywords... use google_ads_ads_update / update_status and google_ads.keywords.* for those.' This directly tells the agent when to select a different tool.

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