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

Annotations already declare readOnlyHint=true, and the description adds meaningful context beyond that: the scoring methodology, included fields, update cadence, and the Gold-tier requirement for history series. No contradictions; the behavior is well disclosed for a read-only index tool.

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 moderately long but dense and front-loaded with the key output definition. The use-case list and update cadence are valuable, though the parenthetical methodology clause could be tightened without losing meaning.

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?

Given no output schema, the description compensates by listing all return fields and the score scale. It also explains the optional history behavior and typical use contexts. However, it does not explain how the target county is selected since no county parameter exists, which is a minor gap for an agent.

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?

The only parameter, 'days', is fully documented in the schema with range, purpose, and tier behavior, so schema coverage is 100%. The description does not add extra parameter semantics, but the baseline of 3 applies because 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 verb 'Returns' and names the exact output: a 0-100 county regulated-facility concentration score. It further specifies methodology (log-scaled z-score of EPA ECHO facility counts across 3,222 counties) and lists the included fields, leaving no ambiguity about the tool's purpose.

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?

Explicitly lists when to call it: for EPA-regulated facilities, polluter/industrial concentration, compliance burden, site selection, Phase I escalation, and premises-pollution underwriting. It does not explicitly contrast with sibling tools or state when not to use it, but the use-case enumeration is clear enough for an agent.

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