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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, covering the safety and mutability profile. The description adds valuable context beyond these: data source (Orphadata/Orphanet), licensing (CC BY 4.0), authentication needs (none), and rate limits (unlimited free). This exceeds the baseline set by the annotations.

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 three sentences, front-loaded with the core action and returns, followed by language support and source details. It is efficient and free of fluff, though the language list could be abbreviated without loss.

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?

The tool is a simple lookup with an output schema present, so return-value details are not needed. The description covers the key access context (source, auth, rate limits) and language options. It does not mention behavior for invalid ORPHAcodes, but given the simplicity and existing output schema, this is not a critical gap.

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% — both parameters have detailed descriptions in the schema, including the ORPHAcode example and the language enum. The tool description does not add substantial new parameter meaning; it merely restates the language list and inheritance mode examples, which are already implied by the schema. This meets the baseline of 3 for high coverage.

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 clearly states the action ('Get') and the specific resource (rare disease by ORPHAcode), and enumerates the exact data returned (inheritance modes, age of onset, disease group/typology). This unambiguously distinguishes it from sibling tools like disease_epidemiology, disease_phenotypes, and disease_lookup.

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 clearly implies the intended use case (when you need inheritance mode and clinical timeline for a rare disease), but it does not explicitly mention when NOT to use it or name alternative tools. Given the presence of closely related sibling tools, explicit exclusions would have been stronger, but the clear scope provides adequate guidance.

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