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

With no annotations provided, the description carries the full burden of behavioral disclosure. It explains the semantic meaning of the returned list (empty vs. non-empty) and frames the tool as an 'anti-injection guardrail,' which is useful context. However, it does not mention potential errors (e.g., invalid agent address) or authorize requirements, which would enhance transparency.

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 exceptionally concise: two sentences that immediately convey the tool's purpose and the key behavioral nuance. It avoids redundancy, front-loads the main verb and resource, and every sentence adds value.

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 tool with one parameter and no output schema, the description is largely complete. It explains what is returned (a list of addresses) and the meaning of empty vs. non-empty lists, which is critical for correct usage. It does not describe the exact return type (e.g., array of strings) but that is strongly implied by the term 'list.'

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 100% coverage with a single parameter 'agent_address' described as 'Ethereum address of the agent.' The description does not add any additional meaning beyond the schema, such as formatting examples or constraints, so a 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 clearly states the tool's purpose: 'Get the list of owner-approved payment destination addresses for an agent.' The phrase 'anti-injection guardrail' adds specific context that distinguishes it from sibling tools like check_payment_allowed, making the resource and its intent unambiguous.

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 provides clear usage context by explaining the guardrail behavior: 'Non-empty list = the agent's smart account can ONLY pay these addresses. Empty = all allowed.' This helps the agent understand when this tool is relevant (e.g., before initiating a payment), though it does not explicitly compare against sibling tools or state exclusions.

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