List all registered Compass sessions

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

The annotations already indicate readOnlyHint and idempotentHint, and the description adds meaningful behavioral detail: sessions is empty and active_session_id is null when no sessions exist. This goes beyond the schema and annotations by documenting the degenerate case.

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 two concise sentences. The primary behavior is stated first, and the edge case is added without unnecessary detail. Every sentence contributes useful 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-parameter, read-only getter, the description covers the key return values and the empty-state behavior. It does not specify the full shape of each session object, but that level of detail is not critical for selecting and invoking this 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?

There are zero parameters, so there is nothing for the description to clarify beyond what the empty input schema already conveys. The baseline of 4 applies because no parameters exist.

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 uses a specific verb ('Return') with a specific resource: the full set of registered sessions plus the current active_session_id. It clearly distinguishes this read-only listing operation from sibling tools like compass_set_active_session or compass_register_session.

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 implies the tool is for reading session state, and the empty/null edge case gives context about what to expect. However, it does not explicitly state when to choose this tool over alternatives such as compass_set_active_session or compass_register_session.

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