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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds value by stating that results are 'ranked terms with HP: IDs', which is behavioral insight beyond annotations. It does not contradict 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 front-loaded with the core purpose and includes examples, but it is slightly verbose with multiple example phrases and could be trimmed without losing meaning. Still effective.

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?

Given the tool's complexity (3 parameters, output schema, rich annotations), the description covers purpose and behavioral context well but falls short on parameter semantics, which are needed for correct invocation. Adequate but with clear gaps.

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 input schema has 0% parameter descriptions, so the description must compensate. While it implies the 'query' parameter is a clinical description through examples, it does not explain 'page' or 'limit' or their optionality. This is insufficient for a tool with 3 parameters.

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 identifies the tool as a text search over the Human Phenotype Ontology (HPO), with specific verb 'search' and resource 'HPO'. It provides concrete query examples and states the use case for mapping clinical descriptions to ontology terms. This distinguishes it from sibling tools like search_within.

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 explicitly states when to use the tool: 'Use to map clinical descriptions to standard ontology terms for rare-disease workups, genomics, or clinical phenotype databases.' It gives clear context but does not mention when not to use it or provide alternatives, which would warrant a 5.

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