Register a signed-in Redfin session

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

The description adds behavioral detail beyond annotations: re-registering the same account_identity updates the existing session instead of duplicating it, which expands on idempotentHint=true. It also discloses the default-active behavior and the effect of mark_active, giving an agent a clearer model of side effects.

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 tight sentences with no filler. It front-loads the core mutating action, then explains update semantics, return value, and activation behavior in a logical order. Every sentence earns its place.

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 low-complexity tool with 3 parameters and no output schema, the description covers the essential behavior, return value, and active-session semantics. It could also mention what happens when no session is active and mark_active is false, but the first-registered-becomes-default rule largely covers that edge case.

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 meaningful semantic value by identifying account_identity as the idempotency key and by explaining the effect of mark_active on session activation, going slightly beyond the schema's property descriptions.

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 names a specific action ('Register (or refresh) an authenticated Redfin session') and a precise resource ('a session keyed by signed-in account identity'). It clearly differs from sibling tools like redfin_set_active_session and redfin_get_session_context by framing this as the registration/refresh entry point that returns a session_id.

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 gives clear context on how to use the tool: register the first session to become default, pass mark_active to set it active, and use the returned session_id for routing per-tool calls. It does not explicitly name excluded cases or alternatives, but the intended usage is strongly implied.

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