login

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

With no annotations provided, the description must disclose behavior on its own. It usefully explains that the password is fetched from the OS keychain and must be set once beforehand, which is valuable context. However, it does not describe side effects such as session creation, failure behavior, or whether an existing connection is required.

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 short and front-loaded: the first sentence states the action, the second explains authentication behavior, and the third gives the prerequisite. Every sentence contributes value with no filler or repetition.

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 single-parameter login tool, the description covers purpose, authentication source, and setup, and an output schema exists. However, it omits whether a prior connection is required, how it interacts with the sibling connect/disconnect tools, and what happens on login failure. These gaps matter in an environment with connection-management siblings.

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 0% description coverage, so the description must compensate. It does add meaning by defining userid as a RACF userid, but it provides no additional format, validation, or usage details beyond that single label. This is minimal but non-redundant.

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 action ('Log in to TSO') and the target resource (TSO) with the userid parameter. It does not explicitly distinguish itself from the sibling tool 'connect', which could be a related but different operation, so it stops short of a 5.

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 a clear prerequisite ('Set the password once via scripts/set_password.py before calling this') and implies when to use the tool, but it does not discuss when not to use it or how it compares with siblings like connect, reconnect, or status. This is adequate but not explicit.

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