EPA Air Quality System (AQS) MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It describes what the tool returns (county list with FIPS codes) and implies it's a read operation, but doesn't mention authentication requirements, rate limits, error conditions, or pagination behavior. The description adds basic context but lacks comprehensive behavioral details needed for a tool with authentication parameters.

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 perfectly concise with two sentences that each serve distinct purposes: the first states the tool's function and output format, the second provides usage guidance with concrete examples. There's zero wasted language, and the information is front-loaded with the core purpose stated immediately.

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 tool with 3 parameters (including authentication parameters) and no annotations or output schema, the description is adequate but incomplete. It explains the tool's purpose and basic usage but doesn't cover authentication behavior, error handling, or return format details beyond FIPS code examples. Given the complexity of API tools with authentication, more behavioral context would be helpful.

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 schema already fully documents all three parameters. The description doesn't add any parameter-specific information beyond what's in the schema. It mentions the output format (county names with 3-digit FIPS codes) but doesn't provide additional context about the 'state' parameter format or the optional authentication parameters.

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 clearly states the tool's purpose with specific verbs ('Get a list of counties') and resources ('within a state with their 3-digit FIPS codes'). It distinguishes from siblings by focusing on county listing rather than summary data or other entity types, and provides concrete examples (Los Angeles County, CA = '037') to illustrate the output format.

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 explicitly states when to use this tool: 'Use this to look up county codes for county-level AQS API queries.' This provides clear context for its primary use case. However, it doesn't specify when NOT to use it or mention alternatives among the many sibling tools, which prevents a perfect score.

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