Register a signed-in Compass session

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

Annotations indicate idempotentHint=true, and the description reinforces this by stating 'Re-registering the same account_identity updates the existing session rather than creating a duplicate.' It also discloses that the first registered session becomes the default active_session_id, adding context beyond annotations.

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 three sentences with no filler, front-loaded with the core action. Every sentence adds value: registration/refresh behavior, idempotency, default active session, and mark_active option.

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?

Given the tool has 3 parameters, no output schema, and good annotations, the description covers the return value (session_id), default behavior, and idempotency. It is complete for a registration tool, especially with sibling tools covering other session management aspects.

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 baseline is 3. The description adds operational context for parameters (e.g., 'Pass mark_active: true to make the newly-registered session active') but does not introduce new meaning beyond what the schema descriptions already provide for each parameter.

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 clearly states 'Register (or refresh) an authenticated Compass session' using a specific verb and resource. It distinguishes from siblings by explaining the key behavior of re-registering the same account_identity updating the session, which is unique among tools like compass_set_active_session and compass_get_session_context.

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 explains when to use the tool (registering or refreshing a session) and mentions the first session becomes default and the mark_active option. However, it does not explicitly contrast with alternatives like compass_set_active_session for changing the active session, which would strengthen guidance.

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