Email login — send OTP

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

The annotation openWorldHint=true suggests side effects, and the description explicitly names the side effect: sending an OTP email. It also discloses that it is public and requires no prior session. This goes beyond the annotation by specifying the exact action and scope.

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 sentence, front-loads the core action, and includes the endpoint as a precise reference. Every phrase earns its place without redundancy.

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 tool without an output schema, the description sufficiently conveys the main action. However, it lacks next-step guidance, such as mentioning that the OTP must be used with auth_email_login_verify, and how the OTP is delivered or expires. This creates a minor completeness gap in the login flow 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 schema covers 50% of parameters descriptively, but the description itself adds no parameter semantics. The 'app' parameter is well-described in the schema, but 'email' only has a format constraint and no semantic description. The description does not compensate for this gap, leaving the meaning of 'email' implicit.

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 action: 'send a 6-digit OTP' for 'Passwordless email login', and includes the endpoint for precision. It is distinct from sibling auth_email_login_verify, which would handle the verification step, thus effectively differentiating purpose.

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: it is a passwordless email login that requires no prior session. This implies when to use it, though it does not explicitly reference sibling alternatives or exclusion conditions. It adequately orients the agent to the start of the login flow.

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