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

The annotations already establish that this is a safe, read-only, idempotent, non-destructive operation. The description adds useful behavioral context by explaining that codes are probed live against the atom feed and that unlisted codes are rejected as invalid_arguments rather than sent upstream.

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?

Three sentences, each doing useful work, with the primary action and key usage rule front-loaded. There is no filler or repetition.

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?

For a zero-parameter discovery tool with strong annotations and no output schema, the description provides everything needed: what it returns, when to call it, why the codes cannot be inferred, and how invalid codes are handled.

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?

The tool takes zero parameters, so there is no parameter documentation burden. The description appropriately focuses on the returned values, namely court/tribunal names and their court codes.

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 states a specific verb and resource: list UK courts and tribunals covered by Find Case Law, including the court code each uses. It also clearly distinguishes this discovery step from the sibling search tool, search_uk_caselaw.

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 explicitly says to call this before narrowing search_uk_caselaw by court and explains why: codes such as "ewhc/comm" cannot be guessed from a court name like "Commercial Court." This gives the agent a clear precondition and a concrete alternative workflow.

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