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

With only readOnlyHint=false in annotations, the description does the real work: it discloses that the session and credential are destroyed while the matter, declarations, and room stamps persist, and that a room departure is recorded first. That is exactly the durable-vs-ephemeral context an agent needs; it omits auth/rate-limit detail but those are minor here.

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?

Four short sentences, front-loaded with the admission requirement and the core effect, with no wasted filler. The bracketed jargon ('NEEDS ADMISSION', 'matter remains... room stamps') is terse but each clause carries new 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 2-parameter session-ending tool with no output schema and minimal annotations, the description covers prerequisites, side effects, and what survives the call. Only a note on what the caller receives or how to re-enter later is absent.

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 coverage is 100% with both parameters fully documented (including the 'optional when bound to exactly one matter' nuance), so the schema carries this dimension. The description adds no parameter-level information beyond what is already structured.

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 and effect: 'Exit Atlas. Ends this session and retires this credential.' That distinguishes it from the generic room tools, though the boundary versus atlas.leave_room is only implied ('if you are inside a room, Atlas records the departure before the session ends').

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 bracketed '[NEEDS ADMISSION: enroll, then atlas.bind_actor]' gives an explicit prerequisite sequence for using the tool. It stops short of naming when NOT to check out or pointing at a genuine alternative among siblings.

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