auth_login

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

With no annotations provided, the description carries the full burden and does so: it returns at once with a link, the link contains no secret, the new key goes to the OS credential store and is never shown, and it is idempotent unless switch_account is true. It even discloses that the current key is retained during a switch.

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?

Front-loaded with the core behavior and the link-return contract, then the follow-up step, then the parameter note. Slightly verbose in places (the secret/link caveat), but nearly every sentence earns its place.

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, and the description explains what the tool returns (an immediate link) plus the follow-up confirmation flow. An agent has everything needed to invoke it correctly and handle the result.

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%, but the description fully compensates for the single parameter: switch_account signs in as a different account or workspace, and the current key is kept until the new one is stored. This is meaningful semantics beyond the schema's bare boolean.

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+resource (sign in to OpenRouter in the user's browser) and describes the actual mechanism (opens the sign-in page, returns a link). It also distinguishes itself from siblings by naming account_status as the confirmation step.

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 explicit when-to-use guidance: finish in the browser, then call account_status to confirm; show the link if the browser didn't open; no-op if already signed in unless switch_account is true. The alternative action (auth_logout) is implicitly separated by the sign-in framing.

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