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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds genuinely useful context the annotations lack: a $0.01 cost per call and the caveat that distances are measured from site reference points and are not a property-safety determination. It still says nothing about result caps, pagination, or behavior when both lat/lon and place are supplied.

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?

Two tight sentences that front-load what is found and where, followed by a cost/limitation sentence where each clause earns its place. Slightly dense packing of the return-field list, but nothing is redundant.

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 usefully outlines the payload contents and warns about distance semantics, which is enough for a zero-required-parameter read tool. The remaining gaps, chiefly radius behavior and what happens when place and lat/lon are both or neither provided, keep it from complete.

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 only 25% (only 'place' is documented), so the description must carry weight, and it does clarify the two addressing modes ('near coordinates or a place'). However, it never explains radius_km (the actual search band, default 10, capped at 50) or that all four parameters are optional, leaving the most operationally important parameter undocumented.

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 gives a specific verb and resource ('Find U.S. EPA National Priorities List sites near coordinates or a place') and even enumerates the returned fields (identifiers, cleanup status, hazard-ranking score, dates, distance, source profiles), which is well beyond a restatement of the name. It does not contrast itself with any sibling such as get_radon_potential, 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?

Usage is only implied: an agent can infer this is the tool for proximity searches around a point or place name. There is no guidance on when to prefer this over nearby environmental siblings, nor any hint about choosing between the lat/lon and place input modes, both of which are optional and mutually redundant.

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