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

Annotations already provide readOnlyHint=true and idempotentHint=true, so the safety profile is covered. The description adds no new behavioral disclosures such as authentication needs, rate limits, or side-effect details; the return-field list largely duplicates what the output schema already specifies. It is consistent with the annotations and mildly informative, but does not go beyond them.

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 sentences, purpose first, and no filler. The long enumeration of return fields is somewhat redundant with the output schema, but it is still compact and informative. A slightly more concise version could drop the field list and point to the schema, but the current structure remains efficient.

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 one-parameter, read-only lookup with an output schema and annotations covering safety, the description is nearly complete. It explains what the tool does, what inputs are accepted, and what the response contains. It does not specify behavior when a regulation is not found or is not tracked by EuroComply, but these are minor gaps for such a simple tool.

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%, listing short name, regulation number, CELEX, and slug with concrete examples. The description condenses this to 'short name, full name, or slug' and introduces 'full name' as an accepted form, which is a small addition not explicitly in the schema's list. Overall the parameter meaning is already well covered by the schema, so the description adds only marginal value.

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 starts with a specific verb and resource: 'Look up a single EU regulation tracked by EuroComply.' It further clarifies the single-record nature by enumerating the full canonical return payload, which distinguishes it from siblings that list regulations, return enforcement actions, or surface deadlines. This is unambiguous.

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 implies when to use the tool (when you need the canonical structured entry for one regulation), but it never names alternatives or states when not to use it. An agent must infer that list_regulations is for a full listing or that upcoming_deadlines is for time-based queries. The usage context is clear but not explicit about routing.

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