douyin_account_login

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

With no annotations, the description carries the full behavioral burden and does so: a real browser window pops up, auto-closes about 2s after a successful scan, self-closes after at most 2 minutes if unscanned, and wait_seconds timeouts do not abort the background session. It also discloses the anti-automation and SMS-verification constraints and the verify_code.txt workaround.

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 window behavior and timeout semantics that govern how to call it, and nearly every sentence adds operational value. Minor redundancy with the schema's headed description and slightly dense bolding keep it from a 5.

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?

There is no output schema, and the description compensates by describing the return states ('scan succeeded' vs 'session still waiting for scan'), window lifetime, and the SMS-verification recovery path. An agent has everything needed to invoke, poll, and recover.

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 the baseline is 3; the description nevertheless adds meaning by explaining that wait_seconds' timeout does not interrupt login and that the session keeps waiting in the background, plus the polling consequence. headed is only restated, so it is not a full 5.

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+resource: logging a user into Douyin via QR scan. The scope (per-account login, distinct from status/logout siblings) is unambiguous, and an agent can tell it is the credential-establishing tool rather than a read or query tool.

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 tells the agent to re-call this same tool when the session is still waiting rather than starting a new login, and gives the condition for setting headed=false (only on CI/servers with no desktop session). It also routes SMS-verification retries through verify_code.txt, which is real alternative-path guidance.

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