list_accounts

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so no destructive behavior needs flagging. The description adds useful behavioral context beyond the annotations: it explains the reachable-account scope, the data returned, and its role as a prerequisite step for other tools.

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 concise sentences with no redundant information. The first sentence states what the tool returns, and the second provides a direct, actionable usage instruction. Every word earns its place.

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?

For a simple, zero-parameter, read-only list tool with an output schema, the description is complete. It explains the purpose, the output fields, the credential-bound scope, and the primary usage pattern (call first). Nothing critical is missing.

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 has zero parameters, so the baseline is 4 and the description has no parameter burden. It does not need to explain parameter meanings because there are none; the description even implies no input is required by saying to call it first to obtain the customer_id.

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 clearly states the action ('List the Google Ads accounts'), the scope ('these credentials can reach'), and the meaningful output attributes (currency, time zone, test account flag). It also sets this tool apart as the entry point for obtaining customer_id, distinguishing it from other list tools like list_campaigns.

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?

The description gives an explicit usage directive: 'Call this first to get the customer_id for other tools.' This provides clear context for when to use it, though it does not explicitly name alternatives or state when not to use it. For a zero-parameter discovery tool, this is still strong guidance.

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