Set the active Compass session

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

Annotations indicate idempotency and that this is not read-only; the description adds meaningful side-effect context: it changes the default session for subsequent tool calls. It also clarifies the relationship with per-call session_id overrides, going beyond the structured fields.

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?

Two sentences, each earning its place: the first states the core behavior, the second adds necessary provenance and override semantics. No filler or repetition of schema details.

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 single-parameter, idempotent state-setter with no output schema, the description provides everything needed to invoke it correctly. It covers what the tool does, where the session_id comes from, and how it interacts with explicit session_id parameters elsewhere.

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%, so the baseline is 3. The description adds value by specifying that the session_id must have been previously returned by compass_register_session and that it affects default routing, which is not captured in the schema's simple 'Session id to make active' text.

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?

Description uses a specific verb ('Switch') and names the exact resource ('active Compass session'), clarifying that it changes default routing for subsequent calls. It also distinguishes itself from registering a session by requiring a session already returned by 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?

States the precondition clearly: the session_id must come from compass_register_session. It also explains when the default can be bypassed (tools accepting explicit session_id override it), giving useful routing context, though it does not explicitly name sibling alternatives.

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