login

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

Annotations mark this as non-read-only and open-world, so the description does not need to establish that it mutates remote state. It adds real behavioral context beyond the annotations: server-side env-var credential fallback and a defined error path ('server reports they're not configured'). It stops short of describing what a successful login yields (session/token) or how a failed captcha is surfaced.

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?

Three tight sentences, front-loaded with the step identity and the required action, followed by the credential-optional rule. No filler or restatement of the tool name.

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?

With no output schema and a small, fully documented parameter set, the description covers the inputs and the credential-resolution behavior adequately. It leaves the return value and post-login session semantics unstated, which is a minor gap for an authentication tool.

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 100%, so the schema already explains all three parameters, including the env-var fallback for username and password. The description adds only the cross-tool hint that the captcha comes from the OCR step, which is marginal beyond what the schema's 'Captcha solution from the get_captcha tool' already states.

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 ('submit credentials + the captcha') and explicitly frames itself as 'Step 2 of login', which cleanly separates it from the sibling get_captcha (step 1). An agent can identify the tool's role in the flow without opening the 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 conditional guidance: omit credentials when VTOP_USERNAME/VTOP_PASSWORD are set on the server, and only prompt the user if the server reports they are missing. It does not address the re-login case (e.g., what to do if a session already exists), which is the one remaining when-to-use gap.

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