google_ads_accounts_list

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

The description explicitly states 'Read-only' and describes the output structure ('one row per accessible customer with id (10-digit), descriptive_name, currency_code, time_zone, and manager flag'). With no annotations available, this provides important behavioral insight, though it does not mention pagination, rate limits, or error cases.

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?

The description is three sentences long, front-loaded with the core purpose, followed by output details and usage guidance. Every sentence adds value with no wasted words.

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 read-only list tool with one optional parameter and no output schema, the description is complete: it explains what is listed, the fields returned, and how to use it in the broader session. No critical information 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 input schema already provides full coverage (100%) with a clear description of the optional customer_id parameter, including format and fallback behavior. The tool description adds no additional parameter semantics beyond reinforcing the usage context, so the baseline score of 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 begins with a specific action and resource: 'Lists all Google Ads accounts accessible under the configured manager (MCC) account or directly under the authenticated user.' It clearly differentiates this tool from sibling tools that list campaigns, ad groups, or ads by focusing on accounts/customers and mentioning the returned fields.

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 provides explicit guidance on when to use this tool: 'Use this at the start of a session to choose which customer_id to pass into subsequent calls.' It also explains the fallback behavior of other tools, helping the agent understand when this tool is needed and how it relates to the broader workflow.

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