Get my saved Zillow searches

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

Annotations already cover read-only/idempotent/open-world, yet the description adds genuinely new behavior: the authentication requirement and its named error, and the non-obvious caveat that session_id is only a registry label and does not control which tab serves the request. This is exactly the kind of auth and side-effect context annotations cannot express.

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, front-loaded with what the tool returns before the operational caveats. Dense with parenthetical detail but no wasted sentences; slightly crammed rather than bloated.

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?

With no output schema, the description compensates by enumerating the returned fields, and it covers the auth precondition, the error case, and the session_id behavior. Nothing an agent needs to invoke 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%, so the baseline would be 3, but the description goes well beyond the schema text: it explains that an unknown session_id errors and that the parameter is a label only, with routing always following the signed-in tab. That is meaningful semantics the schema does not convey.

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 the exact resource (the signed-in user's saved searches on zillow.com) and enumerates the returned fields (name, filters, new-listing count, notification frequency), which cleanly separates it from the sibling zillow_get_saved_homes. An agent can identify this tool without opening the schema.

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 states the precondition clearly (user must be signed in at zillow.com in the bridged tab) and the failure mode if not (SessionNotAuthenticatedError), plus when session_id applies. It does not explicitly route the agent away from alternatives, but the context for use is unambiguous.

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