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

Annotations already provide read only and idempotent hints. The description adds valuable context: it takes no arguments, is free, requires no API key, and explains the critical behavior of including unverified jurisdictions with notes rather than omitting them. No contradictions.

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 a single efficient paragraph, every sentence is informative and earned. It front-loads the core purpose and immediately clarifies an important edge case about unverified jurisdictions.

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 no parameters and no output schema, the description is complete: it names the fields returned, explains the handling of unverified jurisdictions, and sets expectations about cost and authentication. No gaps remain.

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?

With zero parameters and 100% schema coverage, the description correctly states 'Takes no arguments'. Baseline for 0 params is 4; no additional parameter info needed.

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 explicitly states the tool lists every jurisdiction (state, territory, DC) with NPDES authorization status, governing permit, agency details, and preparer-credential gate. It clearly distinguishes from siblings by focusing on a comprehensive list rather than specific permit determination or gate queries.

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 usage for obtaining a full coverage list and clarifies that unverified jurisdictions are included to avoid misinterpretation. However, it does not explicitly mention when to use alternatives like `determine_permit` or `get_credential_gate`, though the context makes it inferable.

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