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

The readOnlyHint annotation already establishes that this is a safe read-only tool, and the description is consistent with that. It adds useful behavioral context by explaining which operation returns public versus custom prompts and what each mode returns, though it omits permission, pagination, or error behavior details.

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 front-loaded with the catalog purpose and then organized as a compact numbered list of operations. Each line maps directly to invocation details, so the structure is efficient and easy to scan.

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 multi-operation router with five parameters and an output schema, the description covers the available operation modes, required parameter combinations, and expected return categories. No critical invocation detail 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?

Schema description coverage is 0%, so the description must carry parameter meaning, and it does: it maps request values, prompt_id, prompt_type='custom', is_custom=True, and workspace_id to each operation. This gives an agent enough detail to construct correct calls across all five parameters.

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 states a specific resource and action: accessing the Ads Libraries prompt catalog through four named operations. It clearly distinguishes the operations from each other, but does not differentiate this tool from sibling tools such as query_data or execute_action.

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 clear invocation context for each operation, including when to use request='menu' versus request='prompt_details' and when custom parameters are needed. It does not provide exclusions or guidance versus sibling tools, so it is strong but not fully complete.

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