start_login

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

Annotations mark this as a non-read-only, open-world operation; the description corroborates by disclosing the concrete side effect (an email is sent) and the two-step handshake with the inbox. It adds real context beyond the annotations but omits rate limits, code expiry, and failure 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?

Two sentences, zero filler, and the action is front-loaded before the endpoint and the next-step instruction. Every clause 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?

With one parameter, full schema coverage, no output schema, and annotations covering the safety profile, the description supplies everything needed to invoke it and continue the flow. Missing only minor operational detail such as code validity window or error cases.

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 coverage is 100% and the single 'email' property already has a descriptive string, so the schema carries the semantics. The description adds only implicit meaning (the email receives the code) and no format or constraint detail beyond what the schema states; baseline 3 applies.

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?

States a specific verb+resource ('Email a one-time login code') plus the underlying endpoint (POST /api/auth/request-code), and the 'browserless onboarding' framing distinct from the sibling complete_login. An agent can tell exactly what this does and where it sits in the flow without opening the schema.

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?

Explicitly names the follow-on sibling ('call complete_login') and the intermediate step (read the code from the inbox), so the when-to-use path is clear. It lacks any when-not guidance (e.g., already authenticated, code still valid), so it falls short of a full 5.

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