login

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

Annotations only declare the safety profile (readOnly=false, openWorld=true, destructive=false). The description goes well beyond: env-var fallback semantics, the shape of failure output (structuredContent.error with code and needsUserInput), and the CREDENTIALS_REQUIRED captcha-reuse behavior. This is rich behavioral disclosure an agent could not infer from structured fields.

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?

Dense and front-loaded — the 'Step 2' framing and captcha requirement come first, followed by credential fallback and error handling. It is long but every sentence carries operational value; no 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?

No output schema exists, yet the description explains the error return shape and recovery path, and covers the credential/config edge cases. An agent has everything needed to call this and handle failures correctly.

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 100%, so the baseline is 3. The description reinforces the optionality of username/password and adds a decision rule (only prompt the user when configuration is missing) plus captcha lifecycle details that the schema alone doesn't convey, nudging it above baseline.

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 ('Step 2 of login: submit credentials + the captcha'), and positions itself in a sequence relative to the get_captcha sibling ('the captcha you just OCR'd'). An agent can distinguish this from get_captcha and logout without opening any 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?

Explicit conditional guidance: omit credentials if env vars are configured, and only ask the user if the server reports they're not configured. It also names the alternative flow (fetch captcha via get_captcha) and instructs reuse over refetching. Nothing is left to inference.

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