start_device_login

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

With no annotations, the description carries the full burden and does a decent job: it discloses that the call yields a URL and one-time code, that a human must open the URL and approve, and that verification is a separate call. It omits code expiry, whether a repeat call invalidates a prior code, and any rate limiting.

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 action and result, then the follow-up workflow. No redundant wording; every clause carries 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?

There is no output schema, and the description compensates by naming the two return values and the human-in-the-loop step. For a zero-parameter initiation tool this is nearly complete, with only expiry/invalidations left unstated.

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 tool takes zero parameters, so the schema is trivially complete and there is nothing extra the description could clarify. Baseline of 4 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 verb and resource ('Start a ChatGPT device-code login for Codex') plus what it returns (URL and one-time code). It also names the sibling login_status, so an agent can separate this initiation step from the status-check step without reading either 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: call this first, the user approves out-of-band, then call login_status to confirm. That effectively routes the agent to the correct sibling. It stops short of stating when not to use it (e.g. if a session is already authenticated) or whether it should be retried.

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