start_email_login

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

Annotations already declare the write-like, non-idempotent, open-world profile, so the bar is lower. The description usefully adds the actual side effect — an email with a confirmation code is dispatched — but says nothing about rate limits, code expiry, or what happens if the address is unregistered.

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 short sentences with zero waste, and the primary action is front-loaded ahead of the backup-email qualifier.

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?

An output schema exists, so return values need not be described, and both parameters are covered. The remaining gap is flow context — how this hands off to verify_email_login and whether the code expires — which an agent would find useful.

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%, so the description has to carry the load, and it does: it explains that 'email' is the target's registered address and that 'backup=true' selects the registered backup email. Both parameters get meaning beyond their bare titles.

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 action and target: it sends a confirmation code to the specified person's registered email, and the second sentence clarifies the backup-email variant. This distinguishes it from the sibling verify_email_login by the start/verify naming, though the description never names that sibling explicitly.

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?

There is no statement of when to call this versus verify_email_login, nor any prerequisites (e.g. that the email must already be registered). Usage is only inferable from the tool name and the word 'start'.

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