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

With no annotations, the description carries the full behavioral burden and does well: it discloses that the password must never be asked for in chat text, is used only for the game login, and is not echoed. It does not describe failure behavior or session persistence, so it falls short of a 5 but is still strong for a security-sensitive action.

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 front-loaded with the core action, followed by the prerequisite check, credential collection method, and security constraint. Every sentence earns its place and there is no filler.

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 login tool with no output schema and no annotations, the description covers the essential invocation path, prerequisite, credential handling, and security constraint. It could be more complete by noting what a successful login returns or how failures should be handled, but it is sufficient for an agent to invoke the tool 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?

Schema description coverage is 100%, so the baseline is 3. The description names the credential parameters and adds security context, but much of that repeats the schema's own descriptions (secret password, username format). The emit_display collection method is useful procedural context, but it does not add substantial meaning about the parameters themselves.

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 begins with a specific verb and resource: "Sign in to Lagos Life." It clearly identifies the tool as an authentication/session-creation action, distinguishing it from session_status by explicitly saying to call session_status first and use login only if not already signed in.

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?

It gives explicit when-to-use guidance: call session_status first, then use login only if the user is not already signed in. It also specifies how to collect credentials via emit_display interaction_mode input, which is precise operational guidance rather than inference.

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