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

With no annotations, the description carries the full burden and does so unusually well: it discloses the $0.03 USDC cost, that the server holds no wallet and never pays, that it returns HTTP 402 payment requirements (x402 on Base, MPP on Tempo), and the exact retry URL. It adds stale flags as a data caveat. It omits pagination/response-shape details, keeping it just under a 5.

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: a hook question, the data description, and the payment mechanics — each earns its place with no filler. The payment sentence is dense but necessary given the no-annotations, paid-invocation context. Front-loading is adequate, though the hook question precedes the concrete deliverable.

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 paid tool with no output schema and no annotations, the description covers what data is returned, its source, the paid nature, the payment protocols, and the retry URL — enough to invoke it without guessing. Only finer return-format details (row structure, ordering guarantees implied by sort) are absent.

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 no enums are declared, so the schema already documents n, beds, sort, and type with defaults and value lists. The description adds no parameter-level meaning beyond that, which is the baseline 3 when the schema does the heavy lifting.

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 question framing and states the deliverable: a county ranking by latest average rent plus 4- and 12-quarter % change, with the data source (CSO/RTB RIQ02). This is a clear verb+resource. It does not, however, explicitly distinguish itself from siblings like county_rent or paid_rent_check, so it stops short of a 5.

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 conveys the key usage condition that this is a paid call and requires an external x402/MPP client, then explains the pay-and-retry workflow. However, it never says when to prefer this over county_rent or paid_rent_check, nor any when-not conditions, so usage selection versus alternatives is left to inference.

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