login

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

With no annotations provided, the description carries the full burden. It discloses the key side effect of saving session cookies, which is valuable. However, it does not mention failure behavior, whether it replaces existing sessions, or other operational details like the browser automation context (only hinted by the headless parameter).

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 two concise sentences, front-loaded with the primary action and including a relevant side effect. There is no extraneous information or repetition of schema details.

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?

Given the tool's low complexity, full schema coverage, and lack of an output schema, the description covers the essential purpose and the critical side effect of saving session cookies. While it omits return value or error handling details, those are less critical for a simple login tool, making the description sufficiently 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 input schema already provides 100% coverage with descriptions for all three parameters. The description adds no additional semantic meaning beyond repeating that identifier is email/phone, so the baseline score of 3 is appropriate.

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 authenticates with Lyft using email/phone and password, using a specific verb and resource. This distinguishes it from sibling tools like status and logout, which have different purposes.

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 implies authentication is a prerequisite for other actions (by saving session cookies for future requests), but it does not explicitly state when to use it versus alternatives (e.g., checking status first) or provide exclusion criteria. Usage is implied rather than directly guided.

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