List messages in a folder

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

No annotations are provided, so the description carries the burden. It discloses that it returns summaries rather than full messages, and that results are newest first via the limit parameter. However, it doesn't mention pagination behavior beyond limit, whether the folder must exist, or what happens with invalid folder paths. For a read-only listing tool, this is adequate but not rich.

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?

A single, well-structured sentence that front-loads the core purpose and then lists the optional filters. No wasted words.

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 list tool with no output schema, the description explains what fields are returned and the ordering. It doesn't mention pagination beyond limit, error behavior for nonexistent folders, or whether the 'since' filter is inclusive. These are minor gaps for a simple read-only listing tool, but with no annotations and no output schema, a bit more detail would help.

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 100%, so the schema already documents all six parameters. The description adds the 'newest first' ordering detail and the summary fields, but doesn't add much beyond the schema. Baseline 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 verb (list), the resource (message summaries in a folder), and the specific fields returned (subject, from, to, date, read status). It also names the filtering dimensions, making it easy to distinguish from siblings like get_message (single message) and list_folders (folders).

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 implies when to use it: when you need message summaries in a folder, optionally filtered. It doesn't explicitly exclude alternatives like get_message for full message content or send_email for composing, but the sibling names and the summary scope make the context reasonably clear.

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