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

Annotations already mark the tool as read-only, idempotent, and non-destructive. The description adds meaningful behavioral context beyond those hints: it reports completeness, names thin legal areas, describes the court hierarchy, and explains the coverage relationship with search_law. This is strong added context for a read-only describe tool.

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 description is dense but front-loaded with the core purpose ('what this service holds and how complete it is'), then enumerates concrete contents and ends with a clear usage directive. It is a single long sentence but every clause adds useful information.

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 tool with one optional read-only parameter and no output schema, the description sufficiently tells an agent what kinds of information it will get and when to call it. It does not specify the exact response shape, but the listed content categories cover the agent's needs.

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 only parameter, session, is fully described in the schema with 100% coverage and is optional. The description does not repeat parameter details, and none are needed because the schema already carries the meaning.

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 names the resource (the corpus the service holds) and specifies exactly what it reports: sources with dates, coverage per legal area, thin areas, court hierarchy, case-number formats, and EU acts that search_law also reads. It also states its purpose ('Call it before telling a user that nothing exists on a topic'), which distinguishes it from search siblings.

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 description gives an explicit trigger: use it before telling a user that nothing exists on a topic. It also clarifies how it relates to search_law for EU acts. However, it does not state when not to use it or how it compares to the other sibling tools.

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