Folder status

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

The description adds an important behavioral caveat about UIDVALIDITY generations, which is beyond what the readOnlyHint and openWorldHint annotations convey. It warns about the validity of UIDs across generations, giving the agent critical context for safe use.

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?

Two concise sentences: the first states the primary output, the second provides an essential caveat. No filler or redundancy, and the most important information is front-loaded.

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 status tool with one optional parameter and no output schema, the description adequately covers what the tool returns and the critical UIDVALIDITY caveat. It is complete enough for an agent to select and invoke the tool appropriately.

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 schema already describes the single 'folder' parameter as defaulting to INBOX (100% coverage), so the description adds no additional parameter-level meaning. Baseline 3 applies because the schema does the heavy lifting.

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 identifies what the tool returns: message counts, UIDNEXT, and UIDVALIDITY for a folder. It lacks an explicit verb like 'get' or 'retrieve', but the resource and output are specific enough to distinguish it from siblings like poll_folder or list_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 provides a clear usage context: check UIDVALIDITY before acting on previously noted UIDs. It implies when to use this tool (before relying on stored UIDs) but does not explicitly mention alternative tools or when not to use it.

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