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

With no annotations, the description carries the full burden and does disclose key behaviors: payment is required, unpaid returns 402, after X-PAYMENT the same URL returns JSON, and empty new sets return 304 or recordCount 0. It omits some details like parameter conflicts and other error codes, but on balance it is transparent about the unusual paid API flow.

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 text is compact and front-loaded with the URL and price, but it is a dense run-on of dash-separated clauses that require careful parsing. No words are wasted, yet the structure sacrifices readability for brevity.

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?

The description adequately covers payment, pricing, and pagination semantics for a paid endpoint. However, there is no output schema and the description only says 'returns JSON' without detailing the response structure, nor does it explain how to combine parameters or obtain a valid X-PAYMENT.

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%, and each parameter already has a detailed description including pricing and behavior. The tool description reinforces this with the pricing model but doesn't clarify interactions between parameters (e.g., id combined with since). Baseline 3 is appropriate because the schema does the heavy lifting.

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 identifies the resource (EPA individual NPDES permit text) and the operations (plain GET, ?id=, ?before, ?since), and even distinguishes it from a new SKU. However, it never uses an explicit verb like 'retrieves' and the message is conveyed through pricing and URL patterns rather than a straightforward statement.

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 explains when to use each parameter variant (newest chunk, older chunk, since watermark) and states the payment prerequisite (HTTP 402 for unpaid). It doesn't mention alternatives among sibling tools or conditions for choosing this over another endpoint, so usage guidance is partial.

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