login_request_code

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

With no annotations, the description carries the full burden and does well: it discloses how the code is delivered (in-app if signed in elsewhere, otherwise SMS) and what each session value means. It omits failure modes such as invalid numbers or whether a new request invalidates a previous code, so it falls short of 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?

Front-loaded with the action and sequencing, then a compact Args block. Every sentence carries information, though the two-session explanation is somewhat verbose relative to its size.

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?

No output schema exists, and the description covers the call's purpose, follow-up step, and both parameters, which is sufficient for an agent to invoke it correctly. Error and retry behavior is not covered, keeping it just under a 5.

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 must compensate fully. It specifies the phone format with a concrete example ('+14155550123') and enumerates the session values with their semantics and default ('watcher' for monitoring, 'mcp' for read tools) — all information absent from the schema.

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 ('Start logging in: ask Telegram to send a login code') and explicitly names the next sibling tool (login_submit_code). An agent can distinguish this from login_submit_code and auth_status without opening any 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?

Gives clear sequencing ('Follow with login_submit_code') and a strong usage instruction ('Ask the user for their phone number rather than guessing it'). It does not state a when-not condition (e.g., what to do if already signed in via auth_status), so it stops short of full exclusion guidance.

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