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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, destructiveHint=false. The description adds useful context: source (US NLM), public domain, no auth, unlimited free. This exceeds the reduced bar for tools with strong annotations, though it doesn't mention edge cases like invalid code handling.

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?

Four sentences, each earning its place: purpose, return contents, language support, and usage context/source. Front-loaded with the core verb+resource, no wasted words.

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?

Simple tool with only 2 parameters and an output schema. The description covers input format, language option, output type, use case, and service provenance. Nothing an agent needs to call it correctly is missing.

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% with both parameters (code and language) fully documented and examples provided. The description echoes language=es and gives examples but adds no meaning beyond the schema, so the baseline 3 applies.

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?

States a specific action ('look up patient-friendly health information') with a specific resource (MedlinePlus Connect) and the exact input (ICD-10-CM diagnosis code). Provides concrete examples (E11, J18.9, I21) and explicitly distinguishes from siblings using ICD-9, RxNorm, and SNOMED.

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?

Clearly gives context: 'Used in EHR/clinical contexts to link clinical codes to patient education materials.' This implies when it is appropriate, but it does not explicitly name sibling alternatives like icd9_lookup or say when not to use this tool. Strong context without explicit exclusions.

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