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

Annotations already declare a safe, idempotent, read-only, open-world read, and the description adds far more: monthly snapshot staleness, per-dataset as_of provenance, US Census geocoding of addresses, and the exact negative-space limits (NPL-only Superfund, newest TRI year, current noncompliance flags only). The 'empty result does not mean the area is free of contamination' caveat is precisely the kind of behavioral framing an agent needs.

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?

Purpose and data sources are front-loaded, then caveats, with essentially no filler sentences. It is a single dense block rather than clearly structured, which costs a point, but every clause carries information.

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?

With no output schema, the description carries the return-value burden and discharges it: each record carries date, distance, and source, and provenance supplies each dataset's snapshot date. Combined with coverage limits and empty-result semantics, nothing an agent needs to call this correctly is missing.

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%, so the schema already documents lat, lon, address, and radius_km including defaults and bounds, making baseline 3 appropriate. The description adds only that address is geocoded by the US Census geocoder and is an alternative to lat/lon, a modest addition over the schema.

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 and resource ('Environmental records within a radius of a US location') and enumerates exactly which three EPA datasets are covered, so scope is unambiguous. It never names or contrasts the sibling tools (drinking_water, due_diligence), so it stops short of the sibling differentiation a 5 requires.

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 gives strong interpretive guidance ('Results are records, not a safety assessment', empty result semantics, and an explicit list of EPA records it does not search), which is real when-to-expect-what context. However, it offers no guidance on when to pick this tool over its obvious sibling due_diligence, leaving tool selection to inference.

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