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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so safety is covered. The description adds real behavior the annotations do not: the 'truncated: true' flag, when it appears, and that raising the limit returns the full set. It does not discuss pagination or rate limits, but for a read-only list tool this is strong added context.

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 purpose, then truncation behavior, then the alternative workflow, in three tight sentences. The trailing Google Ads API doc link is marginally useful but the rest has 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?

An output schema exists, so return structure need not be spelled out, yet the description still names the key fields and the truncation contract. Combined with the limit semantics and the guidance that enumeration is often unnecessary, an agent has everything needed to decide whether to call it and how.

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 the limit parameter's meaning is already documented (baseline 3). The description adds value beyond the schema by tying the parameter to the truncation flag and showing the concrete idiom list_accounts(limit=1000), which explains the practical effect of raising it.

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 ('List accessible Google Ads accounts') and immediately scopes it to Google Ads, distinguishing it from the sibling list_merchant_accounts, list_reddit_accounts, and list_gsc_sites. The return-fields sentence ('names, IDs, status, and whether each is a manager account') makes the resource 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?

Gives explicit when-not guidance: 'Workflows that target a specific account need no enumeration at all' and names the alternative path (get_campaign_performance, run_gaql take customer_id directly). It also explains the escalation path for large lists via a higher limit. Nothing is left to inference.

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