google_ads_accounts_list

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

Despite no annotations, the description clearly indicates the tool is read-only, lists the exact fields returned, and explains the fallback logic for the optional parameter. It does not cover auth requirements or potential errors, but for a simple list operation this is sufficient.

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 a single well-structured paragraph that front-loads the core purpose, lists return fields, and ends with usage guidance. Every sentence serves a distinct purpose with no redundancy.

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?

Given the tool's simplicity (one optional parameter, no output schema), the description fully covers inputs, outputs, and use case. It explains the fallback mechanism and session context, making it complete for an agent to use correctly.

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% (the parameter's description already explains its fallback). The description adds value by contextualizing the parameter as part of session initialization, going beyond the schema's technical definition.

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 uses a specific verb-resource pair ('Lists all Google Ads accounts accessible') and clearly distinguishes its purpose from sibling tools by explaining it returns a list of accessible accounts with identifiers. It uniquely positions itself as the entry point for obtaining customer IDs.

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?

Explicitly states 'Use this at the start of a session to choose which customer_id to pass into subsequent calls' and explains fallback behavior. This provides clear guidance on when and why to invoke the tool, though it does not mention scenarios where it should not be used.

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