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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint. The description adds meaningful behavioral context: the null behavior when there's no active listing and a privacy warning about handling personal data. These go beyond the annotations and help an agent understand data sensitivity and edge cases.

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?

Two dense sentences cover the full scope, the null case, and a privacy note without wasted words. The core purpose is front-loaded, and every clause 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 tool with no output schema, the description enumerates the key fields returned and the null-case behavior, which is sufficient for an agent to know what to expect. It doesn't describe error handling or response format beyond that, but for a single-record read tool with safe annotations, this is adequate.

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 description coverage is 100% and both parameters (zpid, expand) have detailed descriptions. The tool description adds no extra parameter semantics beyond what the schema provides, so the baseline 3 applies.

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 the tool returns the listing agent's full profile (name, license, phone, email, website, brokerage, bio, social links, rating, review count) along with broker and MLS ID. It is specific about the resource ('listing agent's profile') and distinguishes from siblings like zillow_top_agents or zillow_property by focusing on the agent attached to a specific listing.

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 implies when to use it: for a listed home (zpid required) and notes that agent fields are null when no active listing exists. However, it does not explicitly mention alternatives or when NOT to use it, leaving some ambiguity versus sibling tools like zillow_top_agents.

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