list_destinations

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

The description conveys read-only behavior by saying 'list' and explains the meaning of is_primary, which is helpful. However, it does not mention potential error cases, empty results, or whether the list is sorted, so some behavioral details remain unspecified.

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 concise, front-loaded with the main action, and provides necessary clarification about primary email and verified extras in a single sentence. No unnecessary details are included.

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 simple nature of the tool and absence of an output schema, the description adequately explains what is returned (destinations and primary flag). It could be slightly more explicit about the response format, but the context is sufficient for straightforward use.

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 and the schema coverage is 100%, so the baseline score of 4 applies. The description adds no parameter-specific information because none exist.

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 a specific action (list) and resource (forwarding destinations), and distinguishes them from aliases by mentioning primary email and verified extras. This allows an agent to differentiate it from sibling tools like list_aliases.

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 does not explicitly state when to use this tool versus alternatives such as list_aliases or add_destination. Usage is implied by the verb 'list' but no direct guidance or when-not-to-use conditions are provided.

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