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

Annotations already establish readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds genuinely new behavior: manager accounts are listed but not metric-queryable, and the tenant_limit_waiting reason means the connection is saved and will sync later. It does not mention result volume or pagination, but an output schema exists to carry the return shape.

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 tightly written sentences, each with a distinct job: what it lists, a caveat on manager accounts plus the waiting-state interpretation, then the negative routing to a sibling. The tenant_limit_waiting sentence is narrow but earns its place by heading off an unnecessary support request; no filler or repetition.

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 values need not be described, and the annotations cover the safety profile. Combined with purpose, account-type constraints, and the alternative-entity routing, the definition is sufficient to call correctly; the only remaining hole is the unexplained connection_context parameter.

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 50%: the 'source' param is documented in-schema as defaulting to 'ledger', and the description restates that default ('synced data by default'), which is mildly reinforcing rather than additive. The opaque 'connection_context' token parameter is undocumented in both schema and description, so the description does not compensate for the coverage gap.

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 opens with a specific verb+resource ('List accessible Google Ads accounts') and immediately disambiguates the resource by stating that manager accounts appear in the list but cannot return metrics. It also explicitly names what the tool does NOT do (find an ad, campaign, or creative by name), which separates it from entities_lookup_by_name among 150+ siblings.

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?

It names an explicit alternative for the most likely mis-invocation ('use entities_lookup_by_name') and states the condition selecting it. It also pre-explains the tenant_limit_waiting outcome so an agent knows no follow-up support call is needed, which prevents a wrong escalation path.

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