search_entities

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

The readOnlyHint annotation already covers the safety profile, and the description adds meaningful behavior beyond it: the 'up to 3' result limit, that each query executes independently, and that results are keyed by query string. It also states the entity-type scope. This is valuable behavioral context that annotations alone do not provide.

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 purpose is front-loaded in the first sentence, followed by result behavior, multi-query support, and structured Args/Returns sections. It is efficient and each sentence earns its place, though the Args and Returns sections partially restate what the schema and output schema already declare.

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 single-parameter, read-only tool with an output schema present, the description is complete: it covers purpose, entity scope, result limit, multi-query behavior, and return shape. Nothing essential for correct invocation is missing; the only minor gap is lack of explicit alternative routing, which the sibling names make obvious.

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% (query_strings documented with examples and minItems), so the baseline is 3. The description adds value beyond the schema by clarifying multi-query semantics — that queries run independently and results are returned in a dictionary keyed by the query string — which the schema does not convey. The Args section repeats the schema example but the behavioral explanation compensates.

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 verb and resource ('Search for entities... using the Open Targets Platform search API') and names the entity types covered (targets, diseases, drugs, variants, studies). It clearly differentiates itself from the GraphQL-focused siblings (query/batch_query/get_schema) by being a distinct search-API surface, so an agent can tell it apart without opening the sibling schemas.

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 conveys its role as a 'streamlined entity search' and the sibling tools are visibly different (GraphQL query/schema tools), implying when it should be used. However, it never explicitly states exclusions or names alternatives — e.g., it does not say 'for complex GraphQL queries use query_open_targets_graphql instead.' The usage context is implied, not stated.

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