List all registered Homes sessions

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

Annotations already declare readOnlyHint and idempotentHint, but the description adds meaningful context beyond those: it clarifies that the tool does not change account usage, and it explains the external dependency on the fetchproxy browser tab sign-in. This additional behavioral insight (side-effect-free nature and account routing mechanism) is exactly what the agent needs to safely invoke the tool.

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?

Three sentences with zero waste. The primary purpose is front-loaded, followed by the edge case and the crucial account-routing caveat. Every sentence earns its place, and the structure is immediately scannable.

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 parameterless, read-only tool with no output schema, the description is fully complete. It covers the return content, the empty-case behavior, and the operational impact on other Homes tools (account selection via browser tab). An agent can call this correctly with no further guidance.

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?

The tool has zero parameters, so the input schema is trivially complete (100% coverage). The description goes beyond parameter semantics by explaining the output structure (sessions list and active_session_id, including empty/null states). Per the baseline for 0 params, a 4 is appropriate; nothing more is needed for parameters themselves.

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 uses a specific verb ('List'), names the resource ('every registered account label plus the current active_session_id'), and specifies the edge case (empty sessions, null active_session_id). This clearly differentiates it from siblings like homes_set_active_session or homes_register_session, which perform mutations. The purpose is unambiguous.

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 provides clear context on when to use this tool: to view registered sessions without affecting which account is used. It explains that listings are label-only and that account selection is determined by the browser tab the fetchproxy extension is signed into, with instructions to switch tabs to change accounts. However, it does not explicitly name alternative tools or state 'when not to use', so it stops short of a 5.

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