login

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

The annotations are minimal (readOnlyHint=false, destructiveHint=false), so the description carries most of the burden. It clearly states that credentials never pass through the conversation, which is a key behavioral detail about authentication and how credentials are handled. This disclosure is valuable and goes beyond the schema. However, it doesn't describe what happens on success or failure (e.g., session token behavior), but given that the tool is a login, the provided info is sufficient.

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 concise, two sentences with no fluff. It front-loads the purpose, then immediately provides the critical usage instructions. Every word is necessary; no redundant 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?

For a zero-parameter tool, the description covers everything an agent needs: what the tool does, how to configure credentials, and how to call it. Since there is no output schema, the description doesn't need to explain return values, but it's clear enough for an agent to use effectively. The siblings (logout) provide contrast, and the lack of parameters makes this complete.

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 has zero parameters, and the schema description coverage is 100% (effectively covering nothing). The description adds no parameters but explains the configuration mechanism (environment variables) and why no arguments are needed. This is essential context that the schema cannot convey, so the description provides significant value beyond the schema.

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 the tool's purpose: to log in to Formlabs Web Services for remote printing and Fleet Control/Dashboard printers. It uses a specific verb ('Log in') and resource, distinguishing it from siblings like logout and health_check. The context of remote printing and management is clearly conveyed.

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 explicitly instructs that credentials must be set in environment variables (FORMLABS_USERNAME, FORMLABS_PASSWORD, or FORMLABS_ACCESS_TOKEN) and that the tool should be called with no arguments. This is critical because the schema has zero parameters, so the description provides the only usage guidance. It also implies that login is a prerequisite for other operations, though it doesn't explicitly say 'use this before other tools'.

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