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

Annotations already cover read-only, idempotent and open-world behavior, so the bar is lower. The description adds real value beyond that by disclosing the pricing model: free within the daily allowance, then $0.001 USDC per call via x402, plus the breadth of the returned record.

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 compact sentences, front-loaded with the record's purpose followed by the field list and cost model. The field enumeration is long but each item is informative rather than padding.

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?

An output schema exists, so return values needn't be explained, and the safety profile is fully covered by annotations. Adding the X402 pricing context makes the definition self-sufficient for correct invocation, with only sibling differentiation missing.

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% with only one parameter ('urn' = Unique reference number), so the schema already carries the semantics. The description adds no format, example, or validation detail beyond it, matching the baseline 3.

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 resource ('Full register record for one establishment') keyed by URN, and enumerates the attributes returned (type, status, phase, ages, capacity, etc.). It is clearly a single-record lookup, though it never names the sibling tools (search, near) to sharpen the contrast.

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 phrase 'for one establishment' implies this is the single-URN detail lookup versus the plural siblings schools__search and schools__near, but that routing is left to inference. No explicit when-to-use/when-not guidance or prerequisites are given.

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