list-rules

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

No annotations are provided, so the description carries the full burden. It clearly states the return content ('each rule's name and enabled/disabled state') and implies a read-only operation through the 'Use when' vs 'Do not use when' distinction. However, it does not explicitly declare that the operation has no side effects, nor mention auth or error behavior, which is a minor gap for a tool with no annotations.

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 three short, clearly structured sentences with helpful labels ('Use when', 'Returns', 'Do not use when'). Every sentence adds value and there is no redundant information, making it highly concise and well 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 zero-parameter, no-annotation, simple listing tool, the description fully covers when to use it, what it returns, and when not to use it. The existence of an output schema further reduces the burden, so the description is complete for its context.

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, so the schema documents 100% of them vacuously. Per guidelines, 0 params gives a baseline of 4. The description adds useful context about the output, but there are no parameter semantics to explain, so the baseline 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 uses a specific verb ('discovering' / 'list') with a clear resource ('Mail rules') and scope ('whether each is enabled or disabled'). It distinguishes from sibling tools by explicitly naming enable-rule, disable-rule, create-rule, and delete-rule as alternatives for changes, so the purpose is unambiguous.

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?

It explicitly states 'Use when: discovering the Mail rules...' and 'Do not use when: you want to change a rule (use enable-rule / disable-rule / create-rule / delete-rule)', giving clear context and naming alternative tools. This is exactly the level of guidance expected.

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