Register a signed-in Homes.com session

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

Goes well beyond the annotations: it discloses idempotent upsert behavior ('Re-registering the same identity updates the existing entry'), the return value (session_id), and critically that the registry does not affect which account actual requests use — every call routes through the browser tab the extension is signed into. That routing caveat is exactly the kind of non-obvious behavior an agent needs.

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?

Front-loads the core action and payload in the first sentence, then layers idempotency, return value, the key scoping caveat, and the browser-tab routing note. Every sentence carries distinct information with no filler.

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?

No output schema exists, but the description still states the return (session_id). Combined with the label-only caveat and routing explanation, an agent has everything needed to call this correctly and to avoid misinterpreting what registration does.

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 already 100%, so the baseline is 3. The description still adds value by clarifying that account_identity keys the entry and that mark_active:true activates the session 'in the same call,' reinforcing the flag's side effect beyond the schema's one-liner.

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?

Specific verb and resource: 'Record (or refresh) which Homes.com account the signed-in session belongs to, keyed by account_identity.' The added clause that the registry 'is a label only' differentiates it conceptually from the active-session siblings, though it never names homes_set_active_session or homes_get_session_context directly.

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?

Gives clear conditions for use: register a new identity, or re-register to refresh an existing entry, and explains the mark_active flag for immediate activation in one call. It stops short of explicit when-not guidance or naming the alternative tools (e.g., set_active_session) an agent might reach for instead.

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