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

The annotations already declare readOnly, idempotent, non-destructive and closed-world, and the description goes well beyond them: it documents the return envelope (data, schema_url, effective_from, verified_at, id, verification, disclaimer) and, critically, the layering behavior — stacked levels come back as separate entries in `layers` and are never merged. That non-merge rule is exactly the kind of behavior an agent could otherwise get wrong.

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?

Core purpose and scope are front-loaded in the first clause, and the example is placed before the return-shape detail. The middle section is dense with colons and parentheticals, but nearly every clause carries information; only the enumeration of response keys could be trimmed.

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?

There is no output schema, so the description must carry the return contract, and it does: it names each top-level response field, dates it, explains the `layers` semantics, and adds the informational-only disclaimer. Nothing an agent needs in order to call this and interpret the result is 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%, so both required parameters and the optional `domain` are already fully documented, including pointer to list_rule_types and list_jurisdictions. The description adds only a concrete call example, which is mildly useful but does not explain the optional `domain` fallback behavior itself. Baseline 3 is appropriate.

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 verb and resource ("get the rule in force today") plus the scoping to one rule type and one jurisdiction, and adds that the citation is included. The phrase "in force today" implicitly distinguishes it from get_rule_as_of and get_rule_history, so an agent can place it among siblings without opening schemas.

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 temporal qualifier "in force today" plus the pointer to resolve_version ("the version id to record with any decision that relies on it") tells the agent when this tool is the right call and what downstream action follows. It never explicitly says to use get_rule_as_of for past dates or get_rule_history for change tracking, so sibling routing is left partly to inference.

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