registry_login

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

With no annotations, the description must disclose behavior. It adds the session-default server handling and the security preference for passwordStdin, warning about credential exposure in process lists. However, it doesn't mention side effects (e.g., persisting credentials, altering local config), potential return values, or failure behavior, which are common for login tools.

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?

Three concise, purposeful sentences. The first states the action, the second clarifies a key default, and the third gives a security recommendation. No fluff 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?

Given the tool's simplicity, no output schema, and no annotations, the description covers the essential behavior (login, server default, secure password handling). It lacks details on success/failure output or credential persistence, but is reasonably complete for an authentication tool.

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?

Input schema covers all 4 parameters with descriptions, so baseline is 3. The description adds extra context about the server parameter (session default) and reinforces passwordStdin's security advantage beyond the schema text, making the parameter semantics clearer.

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 a container registry.' It names the specific resource type and differentiates from sibling registry_logout (which logs out) and other container/network/image tools.

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 clear context: it is for authenticating to a registry, with the default-server behavior explained. It implicitly recommends using passwordStdin for security, but doesn't explicitly state when to use this tool vs alternatives (e.g., registry_logout or other auth methods). No exclusions are given.

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