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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, covering the safety and side-effect profile. The description adds that it returns data with specific fields and statuses, but does not introduce any behavioral traits beyond what annotations already imply. This is a baseline score because the description doesn't contradict annotations and adds minimal extra behavioral context.

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 longer than the high calibration example but every sentence earns its place: it front-loads the purpose, lists return fields, explains biotech relevance, and gives three example questions. It is well-structured and not repetitive, though it could be slightly more compact without losing value.

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?

Since there is no output schema, the description explicitly lists the fields returned, which is important for agents. It also covers the intended use cases and business relevance. It does not mention pagination or error handling, but those are minor and not necessary for a read-only list tool with annotations covering safety. Overall it is fairly complete.

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 100%, so all parameters (limit, query, since, status) are fully documented in the schema with descriptions and examples. The tool description does not add any additional parameter semantics beyond what the schema provides, such as clarifying format constraints or interactions. Thus it does not go beyond the baseline of 3.

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 exactly what the tool does: it returns EMA orphan medicinal product designations with specific fields (active substance, medicine name, intended therapeutic use, EU designation number, status, and dates). It is a clear verb+resource statement and distinguishes this from other EMA tools by focusing on orphan designations specifically, even though it doesn't name a sibling.

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 provides example queries ('what orphan designations has the EMA granted for rare disease X', 'is drug X an EU-designated orphan medicine', 'recent EU orphan designations') that signal the intended use cases. It also adds context that it is Catalyst-relevant for biotech, but it does not explicitly say when to use this tool over alternatives or when not to use it, so it lacks the explicit exclusion guidance that would merit a 5.

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