sign_in

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 richly: it opens a real browser with the user's existing profile, discloses Chromium's profile-lock behavior, notes Safari cannot be driven, mandates calling complete_sign_in afterward, and prohibits password requests. This goes well beyond a generic 'opens a browser' statement.

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 dense but every sentence earns its place: purpose, label clarification, lock behavior, follow-up, password rule, and Safari limitation. Slightly heavy in the first sentence, but well front-loaded with the core purpose.

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?

Given a 2-parameter tool with no annotations and an output schema present, the description covers the critical workflow: opening the browser, handling locks, and chaining to complete_sign_in. It lacks explicit handling of user cancellation or error recovery, but the core invocation path is fully described.

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 0%, so the description must compensate. It explicitly clarifies that 'name' is just a label, which adds meaning beyond the schema. However, 'url' semantics are only implied as the signed-in page to open, not explicitly defined, leaving partial ambiguity.

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 a specific action: 'Open the user's real installed browser' with their existing profile so they are already logged in. It distinguishes itself from the sibling complete_sign_in by explicitly calling out the follow-up step, and the core purpose is unmistakable.

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?

The description gives clear operating context: call complete_sign_in after the signed-in page is visible, retry if the browser is running, and never ask for a password. It lacks an explicit when-to-use vs alternatives comparison with siblings like browse or list_sessions, but the workflow guidance is strong.

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