list_accessible_accounts

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds useful scope context — results are limited to accounts reachable via the authenticated MCC or direct account, which tells the agent why an expected account may be absent. It says nothing about pagination, result size, or failure behavior for expired credentials with no output schema to fill the gap.

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?

Two short sentences with the core action front-loaded and no filler. The second sentence partially restates the first's accessibility constraint but does so to clarify MCC versus direct-account scope, so the redundancy is mild rather than wasteful.

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 input parameters and no output schema, the description is the only place an agent could learn what a returned account record contains (IDs, names, hierarchy). It covers reachability but leaves the return shape undocumented, which matters for a discovery tool that other calls presumably depend on.

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?

The tool takes zero parameters, so there is no parameter semantics to explain and the baseline of 4 applies. The description correctly avoids inventing filtering options that the schema does not support.

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 gives a specific verb and resource ("List all Google Ads accounts") and narrows scope with "accessible via current credentials," which is more than a restatement of the name. It does not explicitly differentiate itself from nearby siblings such as get_account_hierarchy or get_account_info, so it stops short of a 5.

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?

There is no explicit when-to-use statement and no named alternative, even though the sibling set contains several plausible overlaps (get_account_info, get_account_hierarchy). Usage is only inferable from the word "List" and "accessible," leaving the agent to guess whether this is a discovery step or a substitute for the account-detail tools.

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