evidence_betweenRetrieve curated evidence linking two entities, including supporting and conflicting studies, to answer questions about whether one acts on the other.
Direct curated relations between two entities (either direction) with full cards for the supporting and conflicting studies. Answers questions such as "what is the evidence that A acts on B?".
| Name | Required | Description | Default |
|---|---|---|---|
| a | Yes | ||
| b | Yes |
Changes observed during successful MCP inspections.
v1.2.2Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=false, covering safety and idempotency. The description adds that results include 'full cards for supporting and conflicting studies,' which is useful return-shape context. However, it doesn't disclose directionality semantics beyond 'either direction,' pagination, or limits, so it adds only moderate value over 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?
Two sentences, no filler, and the core behavior is front-loaded. The example question slightly pads the length but illustrates usage usefully, so it mostly earns its place.
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 read-only relation-lookup with sparse parameter docs and no output schema, the description covers the basic purpose and return nature (supporting/conflicting studies) but omits identifier expectations, directionality details, and any limits. It is adequate but not 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 description coverage is 0% for the two parameters a and b, so the description must compensate. It only implicitly maps A and B to entities via the example question, without defining accepted identifier formats, entity types, or direction semantics for each parameter. This meets the minimum but leaves notable gaps.
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 a clear verb+resource: 'Direct curated relations between two entities' with 'full cards for supporting and conflicting studies.' It implies a specific evidence-lookup operation, but it doesn't explicitly distinguish itself from siblings like find_relations or get_relation, so it stops just short of 5.
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 example question 'what is the evidence that A acts on B?' implies when to use the tool, but there is no explicit guidance on when to prefer it over get_relation, find_relations, or find_contradictions. Usage is implied rather than stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.