List all registered Redfin sessions

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

The description adds detail about the empty-session edge case (sessions empty, active_session_id null), which goes beyond the readOnlyHint annotation. It clearly aligns with the read-only and idempotent annotations without contradiction, and the added null-case disclosure provides useful behavioral context.

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 exactly two sentences, each earning its place. The main action is front-loaded, and there is zero fluff or repetition of schema/annotation 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 zero-parameter tool with no output schema, the description adequately describes the return value (sessions list and active_session_id) and the edge case when no sessions exist. Nothing an agent needs to call 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?

There are zero parameters, so the schema coverage is trivially 100%. The description doesn't need to explain parameters; a baseline of 4 applies for a parameterless tool, and the description adds no unnecessary information.

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 'Return the full set of registered sessions plus the current active_session_id.' This is a specific verb-resource pair that distinguishes it from sibling tools like redfin_set_active_session or redfin_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 does not explicitly state when to use this tool versus alternatives like redfin_set_active_session. However, the purpose is so specific that usage is implied—one would call this to inspect current sessions. There is no explicit 'when not to use' or mention of alternatives, so it only reaches 'implied usage'.

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