auth_browser_login

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

With no annotations, the description carries the full behavioral burden. It discloses the key side effects and behavior: saving cookies/localStorage/sessionStorage, opening a visible window when headed, auto-filling credentials, and the exact completion-detection logic. It does not mention whether an existing profile is overwritten or what happens on failure, but the core behavioral contract is clear.

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 well-structured and front-loaded. The first sentence states the core action and outcome; the following sentences cover interaction mode, credential handling, secrets, and success detection. No redundant words or filler.

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 an 11-parameter tool with no annotations and no output schema, the description covers the essential flow, secret handling, and completion criteria. It does not describe the return value or error/edge-case behavior (e.g., profile overwriting, timeout result), but it gives an agent enough to invoke the tool correctly in most cases.

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. It adds important meaning beyond raw schema: profile `name`, `headed=true` semantics, using 'env:VAR' for secret credentials, and how `success_url_pattern`/`success_selector` drive completion detection. Some parameters like `timeout_s` and the selector parameters are not explicitly explained, though their defaults make them inferable.

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 uses a specific verb+resource: 'Log in with a real browser and save the session (cookies, localStorage and sessionStorage) into profile `name`.' It also differentiates from sibling auth tools by stating it works for 'any login incl. SSO/MFA/OAuth redirects,' which signals this is the general browser-based login tool rather than a specialized OAuth or import flow.

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?

There is clear usage context: it works for any login including SSO/MFA/OAuth, and headed mode is described for user interaction or MFA. It does not explicitly name sibling alternatives or state when to choose auth_oauth_login or auth_import_storage_state instead, so it stops short of full when/when-not guidance.

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