i_login_send_sms

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

With no annotations, the description carries the burden and does disclose real behavior: it opens a browser, triggers an outbound SMS to a real phone number, and the resulting code expires in 3 minutes. It omits rate limits, SMS cost, and whether a browser session must remain alive between the two calls.

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, front-loaded with the purpose before the handoff instruction, with no filler. Slightly compressed phrasing ('fills the phone number') costs a bit of clarity but no real waste.

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 one-parameter, no-output-schema step tool, the description covers the essential contract: what it does, what it produces (an SMS code), and the time-bounded next step. Failure modes (invalid number, browser launch failure) and return payload shape are left unstated but are secondary.

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?

There is a single parameter at 100% schema coverage, and the schema already explains that it is the phone number that receives the code. The description adds nothing further about format, country code, or validation, so the 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 action set (opens a browser, fills the phone number, requests a verification code) and labels itself 'Step 1 of SMS login', which cleanly separates it from the sibling i_login_with_sms that consumes the code. An agent can identify the tool and its role 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 specifies the follow-up: call i_login_with_sms with the received code within 3 minutes. That is strong sequencing guidance, but it never names when NOT to use this (e.g., i_login_with_password or i_login_with_cookie alternatives) or what to do if the SMS never arrives.

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