Sign In with Email + Password

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

Annotations already flag readOnlyHint=false and destructiveHint=false; the description goes beyond them by disclosing the side effect (account creation when `register: true`) and the exact token shape prefix `utok_`. It does not cover failure behavior (wrong password, duplicate email) or rate limits, which would be needed for a 5.

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?

A single dense sentence that front-loads the core action, then the conditional branch, then the return value. No wasted words and nothing important buried.

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 no output schema, the description usefully inlines the return shape (`{ token: 'utok_...', user }`) and how to attach the token, which is exactly what an agent needs for the next call. Error paths and token lifetime are the only notable omissions.

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%, so all four parameters are already documented in the input schema, and the description mostly restates the `register` behavior found there. The `name` parameter is not mentioned at all in the description. Baseline 3 is appropriate when the schema does the heavy lifting.

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 and resource ('Authenticate an existing Unseen account using email and password') and adds the registration variant, so the agent knows exactly what the tool does. It does not explicitly contrast itself with the auth_request_otp/auth_verify_otp siblings, which is the one missing differentiator.

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?

Clearly frames the two modes: log in with existing credentials, or pass `register: true` to create an account. It also explains what to do with the result ('use in Authorization: Bearer <token> or authToken'). It stops short of saying when to prefer this over the OTP siblings.

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