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

The annotation only supplies readOnlyHint=false; the description carries the real behavioral load by disclosing the side effect (a leaving stamp is appended to the declaration) and two important non-effects (session is not ended, no authority is granted). This scoping is exactly what an agent needs before invoking a state-mutating call.

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 short sentences with zero waste, and the most decision-relevant item (the admission prerequisite) is front-loaded in brackets. Nothing repeats the schema or the annotations.

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 no-output-schema, mutation-flagged tool, the description covers what the call does, what it does not do, and the precondition. The only gap is that it never names where the agent lands/continues next (enter_room, checkout), but that is a minor omission.

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%: both actor_token and matter_id already document their origin (atlas.enroll/atlas.authenticate, atlas.bind_actor) and the optionality condition. The description's admission prerequisite is consistent with that but adds no new parameter-level information, so the baseline 3 applies.

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 concrete verb and resource (return from the current room to the hall) and names the side effect (appending a leaving stamp). It is distinguishable from its closest siblings: enter_room is the inverse, and the explicit 'does not end the session' separates it from checkout.

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?

Leads with the precondition '[NEEDS ADMISSION: enroll, then atlas.bind_actor]', which tells the agent exactly what must happen first. The closing 'does not end the session and does not grant authority' implicitly routes the agent to checkout for termination, but no alternative tool is named outright, so it falls just short of a 5.

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