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

Annotations already declare readOnlyHint=true and openWorldHint=false, and the description usefully adds a real behavioral trait: a per-call cost of $0.005 USD with two payment paths (x402 or API key). It does not disclose result size, pagination, or completeness behavior for what could be a long version list.

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 short sentences, front-loaded with the capability and ordering before the payment note. No filler, though the pricing sentence, while operationally relevant, is not about how to invoke the tool correctly.

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 states what is returned (all versions, ordered by applies_from) and the cost model, which is adequate for a simple two-parameter read tool with no output schema. The remaining gap is that 'key' is never characterized, leaving a required parameter semantically thin.

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 only 50%: 'jurisdiction' is documented in the schema ('Omit for all jurisdictions') while 'key' has no schema description and the tool description never explains what key identifies (presumably a rule identifier) or its format constraints. The description fails to compensate for the coverage gap.

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 gives a specific verb and resource ('Get every version of a rule') plus the ordering contract ('ordered by applies_from'), which clearly distinguishes a history lookup from the sibling get_rate. It never names that sibling explicitly, so the differentiation is implicit rather than stated.

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?

Usage is only implied: 'every version' suggests this is for historical/versioned lookups while get_rate would be for a current value, but no when-to-use, when-not, or named alternative is provided. An agent must infer the routing decision from the word 'history'.

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