login_link

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

No annotations are provided, so the description carries the full burden. It discloses that an email is sent, that the code is one-time, and that no password is needed. This gives the agent a clear behavioral model. It doesn't mention rate limits or code expiration, but for a simple initiation tool this is adequate.

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 compact and efficient, using two short sentences to convey purpose and follow-up action. It is well-structured with the key behavior front-loaded and no extraneous information.

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 tool with one parameter and no output schema, the description covers the essential flow: it emails the code and points to the next verification step. It could mention code expiration or whether the user must already exist, but given the tool's simplicity, it is largely complete.

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 has only one parameter (`email`) with 0% description coverage. The description adds meaning by clarifying that the email is the recipient of the magic link, which is not fully explicit in the schema. This compensates for the lack of schema-level descriptions.

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 function: email a one-time login code/magic link to the given email address. It distinguishes itself from siblings like `verify_login` and `login` by specifying the initiation step of a passwordless login flow.

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 clear usage context by describing the passwordless login flow and explicitly instructing the next step (call `verify_login` with the code). However, it doesn't explicitly mention when to use this over alternative auth tools like `login` or `use_token` beyond the passwordless context.

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