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

Annotations already declare it is a non-read-only, non-destructive, open-world mutation, so the description only needs to add context. It does: the default state (secondary), the return artifact (event snippet for site or GTM), and the reassuring fact that spend is unaffected. It omits permission requirements and whether the created action can be undone.

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 short sentences, each carrying distinct information: what is created, what is returned, the default status, and the spend caveat. The key facts are front-loaded with zero filler.

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?

With no output schema, the description helpfully names the return value (event snippet for site or GTM), and annotations cover the safety profile. For a 9-parameter mutation tool it could say more about account selection and which category/counting combinations are typical, but an agent has enough to call it correctly.

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 67%, so most parameters are already documented. The description adds meaning only for 'primary' by explaining the secondary default; name, category, and click_lookback_days remain undocumented in both places, so it does not fully compensate for the coverage gap. Baseline 3 is appropriate.

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 states a specific verb and resource ('Create a website (WEBPAGE) conversion action') and adds the useful outcome 'return its event snippet for the site or GTM'. It is clearly distinct from google_ads_update_conversion_action by verb, but never addresses the closest ambiguous alternative, gtm_setup_conversion, which also sets up conversion tracking.

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?

'Created as secondary unless primary=true' gives one conditional default, and 'Doesn't change spend directly' implies this is a setup step rather than a bidding change. However, there is no explicit when-to-use vs when-not guidance, and no routing to gtm_setup_conversion or google_ads_update_conversion_action, leaving the agent to infer the workflow.

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