cx_login

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

With no annotations provided, the description carries the full burden of behavioral disclosure, and it does so well. It reveals that the password is only used in memory, is never logged or returned, and specifies the exact return code login_verification_required in the MFA case. This is meaningful, non-obvious behavioral context.

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 only two sentences yet covers purpose, security behavior, a conditional return value, and an alternative tool. It is front-loaded with the main purpose and contains no filler, so 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?

For a simple login tool with two self-explanatory parameters and an output schema present, the description is complete. It covers success prerequisites implicitly, security handling, MFA behavior, and the fallback to cx_import_cookies, leaving no critical gap for an agent to call it 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?

The schema has no descriptions and 0% coverage, so the description must compensate. It adds security-relevant context about the password parameter, but it does not explain parameter formats, constraints, or the meaning of username beyond what the name already implies. The parameters are obvious enough that this is adequate but not rich.

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 logs into Xuexitong/Chaoxing with a username and password, using a specific verb and explicit resource. It also distinguishes itself from the sibling cx_import_cookies by describing the MFA fallback path, making the tool's role unambiguous.

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 gives an explicit conditional usage rule: if two-step verification is required, the agent should guide the user to log in via browser and then use cx_import_cookies instead. This directly tells the agent when to use this tool and when to switch to an alternative.

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