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

No annotations are provided, so the description carries the full behavioral burden. It discloses the two pieces of state returned, and the read-only nature is implied by "check," but it does not say what happens when the caller is not signed in (error vs. a signed-out result), nor anything about cost or side effects.

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?

One sentence, front-loaded with the check, with zero filler. Nothing could be removed without losing information.

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 zero-required-parameter read tool with no output schema and full schema coverage, the description covers what is returned and why an agent would call it. The only gap is the signed-out outcome, which matters for deciding whether to call login next.

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 single parameter (notification_message) is fully documented in the schema at 100% coverage, so the schema does the work. The description adds no additional meaning about when that fallback message is surfaced, which is the baseline-3 case.

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?

States a specific verb ("check") and resource (session/sign-in state plus current character), which is enough to tell it apart from login/register (which establish a session) and get_my_profile (which returns profile detail). It stops short of explicitly naming those siblings, so it is clear but not maximally differentiated.

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?

Usage is only implied: the phrase "whether you are signed in" suggests a pre-flight check before authenticated actions, but there is no explicit when-to-use, when-not, or named alternative (e.g., use login if this reports signed out).

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