email

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

With no annotations provided, the description carries the full behavioral disclosure burden. It clearly states it performs validation only, does not send an email, and returns a boolean. This is sufficient for a simple validation tool, though it does not detail edge cases or specific regex behavior.

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 with no wasted words. It front-loads the main purpose, adds a crucial caveat, and states the return value. Every sentence earns its place.

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 tool is simple, has no parameters, and no output schema. The description fully covers what the tool does, what it does not do, and what it returns. There are no critical gaps for an agent to invoke or interpret it correctly.

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 in the input schema, so the baseline is 4. The description adds no parameter-specific details, but none are needed since the schema contains no properties and the description explains the operation on the input string.

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: it validates a string against common email format. It also explicitly differentiates itself by noting it does NOT send an email, which removes ambiguity. The verb 'validates' and resource 'common email format' are specific and distinct from sibling tools.

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 clear context that this is for validation only and explicitly warns it does not send an email, which is a useful exclusion. However, it does not mention alternative tools or explicit when-to-use guidance beyond that, so it stops short of a 5.

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