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

Annotations already establish the read-only, closed-world safety profile, so the description's job is to add context, which it does: it discloses the three categories of returned data (coverage description, facility counts, in-violation counts) and the temporal caveat that counts reflect the current monthly ECHO Exporter snapshot with vintage in API status. That vintage note is genuinely useful context not present in any structured field.

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 sentences, both load-bearing: the first defines the payload, the second qualifies data freshness. The parenthetical program enumeration is long but it is the substance of the tool's value rather than filler. Slightly dense, but front-loaded and free of repetition.

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 and no parameters, the description carries the burden of describing returns, and it does so at a field-group level (coverage, facility count, violation count). It stops short of stating the exact field names or whether program identifiers returned here are the same ones accepted elsewhere, which would have made it fully self-sufficient.

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 tool takes zero parameters, so there is no parameter semantics to explain and the baseline of 4 applies. The description correctly spends no words on argument behavior.

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 ('List the EPA programs unified in this dataset') and then enumerates the six programs by name, so an agent knows exactly what comes back. This is clearly distinguishable from the sibling tools, which all operate on facilities or compliance summaries rather than the program catalog itself.

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 implied — this is evidently the discovery/catalog call that precedes facility-level queries — but the description never says so explicitly, nor does it name a sibling like search_facilities as the follow-on step. Nothing is stated about when this tool is inappropriate or redundant.

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