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

Annotations already declare readOnlyHint/idempotentHint/non-destructive, so the trailing "Read-only." is redundant, but the description adds real behavioural context the annotations cannot: what a goal actually controls (biddable Conversions column + Smart Bidding), the category/origin identity model, and the campaign-override behaviour. Pagination and result limits remain unstated.

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-loaded with the core purpose and the sibling distinction before the explanatory examples. The category/origin enumeration is long but each pair maps a real value to a concrete signal, so the length is buying information rather than padding.

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?

An output schema exists, so return-value structure need not be described, and annotations cover the safety profile. The remaining gap is the undocumented customer_id scope parameter; otherwise the conceptual context is unusually complete for a list tool.

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 0%, so the description must carry the parameter burden. It explains campaign_id well ("also see that campaign's overrides"), which is the non-obvious optional param, but customer_id is never described in either the schema or the description.

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 ("Lists Google Ads CONVERSION GOALS") and immediately scopes it against a near-neighbour concept: it governs which conversion CATEGORY is primary, "not a single action's primary_for_goal flag." An agent can distinguish this from list_conversion_actions and list_custom_conversion_goals without opening any 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 a clear when-to-use rule ("In goal-based accounts THIS governs bidding ... the correct way to demote/promote 'local actions' too") and a conditional extension ("Pass campaign_id to also see that campaign's overrides"). It never names the sibling tools it supersedes, so routing is guided by concept rather than by explicit alternative.

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