Inbox counts

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

With no annotations, the description carries the full burden. It does disclose the behavioral output — per-folder counts plus unread counts across four named folders — which tells the agent what kind of result to expect from a side-effect-free read. It says nothing about permissions, scoping to the authenticated user, or anything beyond the returned figures, so meaningful gaps remain.

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-formed sentence that front-loads the two things being counted and enumerates the folders. No filler, no restatement of the tool name.

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 zero-parameter, no-output-schema counter, the description supplies essentially everything an agent needs: the four folders covered and the two metrics returned. It doesn't specify the result shape (e.g., a map of folder to counts), but that gap is minor for a tool this simple.

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 takes zero parameters, so per the rubric the baseline is 4. There is nothing for the description to clarify beyond the empty schema.

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 states a specific verb+resource: counting threads per folder (inbox, sent, archived, spam) and counting unread ones. That clearly separates it from siblings like list_threads or read_thread, which return content rather than aggregates. It lacks an explicit naming of those siblings, so it's clear but not fully differentiated.

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?

There is no when-to-use guidance, no statement of prerequisites, and no reference to alternatives such as list_threads for the actual messages. The use case (getting an overview of folder volume) is only implied by the content of the description.

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