facilities_by_zipList EPA-regulated facilities in a US ZIP code from the EPA Facility Registry Service (FRS). Returns each facility once with all the EPA programs (RCRAINFO, NPDES, AIRS, TRI, etc.) it's regulated under. Keyless.
| Name | Required | Description | Default |
|---|---|---|---|
| zip | Yes | 5-digit US ZIP code, e.g. "94704". | |
| limit | No | Max rows to fetch (default 20, max 50). |
Changes observed during successful MCP inspections. Dates show when Glama detected each change.
Input schema / examplesAdded value: +[
+ {
+ "zip": "94704"
+ },
+ {
+ "limit": 30,
+ "zip": "10001"
+ }
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint. The description adds value by explicitly noting the deduplication ('Returns each facility once') and the keyless access, providing context beyond the annotations.
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 two sentences with no unnecessary words. The first sentence states the primary purpose, and the second adds key details (deduplication and keyless access). It is front-loaded and efficient.
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 the tool's simplicity (2 parameters, no output schema, rich annotations), the description covers all essential aspects: purpose, return format, deduplication, and authentication. It is fully adequate for an agent to understand and invoke the tool correctly.
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 baseline is 3. The description does not add new parameter details beyond the schema (e.g., it mentions ZIP code but the schema already describes it). No additional parameter semantics are provided.
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 uses a specific verb ('List') and resource ('EPA-regulated facilities in a US ZIP code'), clearly distinguishing it from the sibling 'facilities_by_state' by scope. It also explains the deduplication behavior and mentions the keyless access.
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 description states 'Keyless', indicating no API key is required, which is a strong usage hint. It implicitly differentiates from sibling tools like 'facilities_by_state' by specifying ZIP code scope. However, it does not explicitly state when not to use or mention alternative tools.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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