List a folder

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the agent knows it's safe. The description adds value by stating the default ordering ('newest first'), but it does not disclose other behavioral traits like pagination via cursor or limit behavior. With strong annotations, the description is adequate but not exceptional.

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 two sentences, front-loading the purpose and then adding guidance. Every sentence is necessary and contributes to understanding. There is no fluff or 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?

The description covers the core functionality and provides sibling guidance, but it lacks details about parameters like pagination (cursor), limit, and sorting options. Given there are 5 parameters and an output schema, the description is minimally adequate but could be more helpful, especially around pagination and limit behavior.

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%, meaning the description doesn't explain any parameter meaning. While the schema provides defaults and enums, the description fails to add context beyond what is in the schema. For example, it doesn't mention that 'cursor' is for pagination or that 'sort_by' can be used to change ordering. The description should compensate for low schema coverage but does not.

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: 'List messages in one folder, newest first by default.' It specifies the verb (List), resource (messages in one folder), and default ordering. It also distinguishes from siblings by mentioning folder_list for discovering folder ids and mail_search for selective queries.

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 explicit guidance: 'Use `folder_list` to discover folder ids. For anything selective, prefer `mail_search`.' This tells the agent when to use this tool and when to use alternatives, making the decision clear.

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