Set the active Redfin session

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

The description discloses that the tool changes default routing state for subsequent calls, which goes beyond the annotations (readOnlyHint=false, idempotentHint=true). It also notes the override behavior. It does not describe failure behavior for invalid/unregistered session IDs, but the core stateful effect is transparent and does not contradict the 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?

Two sentences, each earning its place: the first states the primary action and effect, the second provides the prerequisite and the override behavior. 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 simple state-setting tool with one parameter and no output schema, the description is complete: it defines the action, the prerequisite for the parameter, and how the default interacts with explicit session_id parameters. No critical information needed for calling it correctly is missing.

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% and the schema describes session_id as 'Session id to make active.' The description adds important semantic meaning by requiring that the session_id was previously returned by redfin_register_session, which is not in the schema. This helps the agent understand the provenance requirement.

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 states a specific verb ('Switch') and resource ('registered session') and clarifies that this sets the default routing for subsequent tool calls. It clearly distinguishes this tool from siblings like redfin_register_session (which creates sessions) and redfin_get_session_context (which reads session info).

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?

It explicitly says to pass a session_id previously returned by redfin_register_session, giving a clear prerequisite. It also explains that tools accepting an explicit session_id override this default per-call, which tells the agent when the default applies and how to bypass it. It does not explicitly name alternative tools, but the guidance is sufficient for correct usage.

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