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

Beyond the `readOnlyHint: true` annotation, the description adds behavioral context by stating it is 'Pure computation' and 'free'. This manages user expectations regarding external dependencies or costs, which is helpful operational transparency.

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 a single, highly effective sentence that encapsulates the entire tool's function and limitations efficiently. Every word contributes to clarifying the tool's boundaries.

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?

Given the low complexity and single parameter, the description is complete. It provides the necessary guarantees (no network calls, pure computation) and limitations (syntax only, no lookup) that an agent needs to use 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?

Schema description coverage is 0%, but since there is only one parameter and it is clearly named 'email', the description does not need to define the input value. It is optimally concise, earning a high score without repeating schema data.

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 ('Check') and clearly defines the target resource ('email address'). It distinguishes the function by stating it checks syntax, differentiating it from potential lookup or sending 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?

It provides explicit usage constraints by stating what it does not do ('no mailbox lookup, nothing is sent'). This helps the agent decide immediately if this tool fits the user's specific request for verification vs. validation or sending.

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