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

Annotations already establish readOnly, idempotent, openWorld, and non-destructive behavior. The description adds meaningful context beyond those: 'no auth required,' public-domain data source, 1M+ facility coverage, and the specific compliance fields returned. It does not discuss pagination or rate limits, but those are not critical for this read-only search tool.

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 compact and front-loaded: purpose in the first sentence, output details next, parameter strategy third, and source/auth context last. Every sentence adds information; there is no filler or repetition of schema content.

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?

For a read-only facility search with 5 optional, fully schema-documented parameters and an output schema, the description covers all essential operational context: search modes, returned fields, coverage, data source, and authentication. It does not need to explain return values in detail because an output schema exists, and pagination/defaults are already in the input schema.

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%, so the baseline is 3, but the description adds value by tying parameters to search strategies: 'Use zip_code for location-based discovery, or facility_name with state for targeted searches.' It also reinforces the state requirement when using facility_name alone, which helps agents pick the correct combination before calling.

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 opens with a specific verb and resource: 'Search EPA-regulated facilities across all environmental programs by ZIP code or facility name.' It enumerates the returned data fields, which distinguishes this general facility search from sibling tools like facility_detail or violations without needing to inspect their schemas.

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 explicit usage guidance: 'Use zip_code for location-based discovery, or facility_name with state for targeted searches.' This clearly instructs when each parameter mode is appropriate. It stops short of naming sibling alternatives or stating when not to use this tool, so it lacks full exclusionary guidance.

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