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

Annotations already declare readOnlyHint, destructiveHint=false and openWorldHint=false, so safety is covered; the description adds real value beyond that by disclosing the data source (EPA ECHO), the breadth of the returned profile (address, county, compliance status, inspections, enforcement, penalties, per-program detail), and a reliability disclaimer. It does not address response size or latency for a record that spans six programs, which is the only notable gap.

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 the action and key, then scope, then contents, then a caveat — a logical order with no filler. The enumeration of six EPA programs is long but earns its place by telling the agent what the response actually covers; minor tightening is possible.

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 burden of describing returns and does so thoroughly (profile fields, compliance, inspection/enforcement history, penalties, per-program detail, source system). Combined with the data-quality caveat, an agent has everything needed to call it and interpret the result.

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 the single parameter already documents itself with an example ('FRS Registry ID, e.g. 110000123456'). The description only reinforces that the ID must be an FRS Registry ID, adding no format, validation, or lookup guidance beyond the schema, so 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 and resource ('Look up one US regulated facility') plus the exact identifier type (FRS Registry ID). It is clearly distinguishable from siblings like search_facilities and list_facilities_with_violations because it is a single-record retrieval keyed on an ID rather than a search or list.

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 implies the prerequisite (you need a Registry ID) and gives a meaningful scope caveat ('screening data, not a Phase I Environmental Site Assessment'), which tells the agent what this data is and isn't fit for. It stops short of explicitly routing to alternatives such as 'if you lack an ID, use search_facilities'.

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