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

Beyond the readOnly/openWorld annotations, the description discloses pricing ($0.002 USDC), the payment rails (x402 on Base, Solana, Arc), that failed calls are not charged, and the result ordering (yearly rows, newest first). It omits error behavior when a PIN is not found and rate limits, which keeps it off 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?

Front-loaded with what is returned, then the exclusion, ordering, and cost — no filler sentences. The first sentence is a long run-on that packs five field names, which slightly hurts scannability, but nothing is wasted.

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?

An output schema exists, so return structure need not be explained, and the description still summarizes the payload fields and their granularity. Combined with the ordering, the owner-name exclusion, and full billing semantics, an agent has everything needed to call it correctly and predict cost.

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% and already documents the 14-digit digit-only PIN (dashes allowed) and the limit range 1-20 with default 5. The description only restates the PIN format and adds the notion of yearly rows, so it adds little beyond the schema — 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?

States a specific verb+resource: Cook County assessor parcel records retrieved by 14-digit PIN, and enumerates the fields returned (assessment class, township, neighborhood code, address, ZIP). It also names the source portal, which helps distinguish it from the nearby `realestate_cookcountyassessor` sibling, though it never explicitly routes against that sibling.

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 negative constraint 'Owner names are not returned' implicitly tells the agent not to use this tool for ownership lookups, which is useful. However, no alternative tool is named and no preconditions (e.g., PIN must exist in Cook County, exact-match requirement) are given, so usage is only implied.

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