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

Annotations already establish that this is read-only, idempotent, and non-destructive. The description adds useful transparency by specifying exactly what the response contains: the latest value, 1-year and 5-year-ago values, and percent change. This is valuable because there is no output schema to convey that information.

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 a single well-structured sentence with no filler. It front-loads the core operation, states the geographic scope and data source, enumerates the returned values, and ends with the input instruction. Every phrase 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 one-parameter, read-only lookup tool with no output schema, the description is largely complete: it defines the input, geographic scope, metric, and response contents. Minor absences like currency units or data freshness are not critical given the tool's simplicity and strong annotations.

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 is only one parameter, region, and schema description coverage is 100%. The description repeats that a region name or id can be passed, but adds no meaning beyond the schema, which already provides concrete examples like 'Austin, TX' and 'Texas.' Baseline 3 is appropriate because the schema carries the semantic weight.

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 opens with a specific verb and resource: 'Get the typical asking rent for a metro or state.' It names the underlying Zillow Observed Rent Index and the exact time-frame values returned, which clearly distinguishes it from sibling tools like realestate_home_values or realestate_trend.

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 provides a clear context for use—rent data for metros/states—and instructs the caller to 'Pass a region name or id.' However, it does not explicitly contrast with alternative real-estate tools or state when not to use it, so the routing guidance is mostly implied.

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