Generate Evidence
Build the evidence. Do not fill the gap with narrative.
ProductBooks tools exist to generate missing proof for the stage you are trying to pass.
Use tools after a stage shows what still scores zero.
Diagnostic module
Tool doctrine
The tool layer is static and explanatory. It exists to clarify inputs, outputs, and how tools support the ProductBooks evaluation system.
Purpose
Tools generate evidence, not verdicts
Each operator is designed to create stage-specific proof such as problem interviews, behavioural tests, or payment signals after an evaluator identifies a gap.
Inputs
Use the evaluator output as the brief
The safest input is the unresolved signal surfaced by the stage. ProductBooks does not ask the tool layer to reinterpret the stage or predict the answer.
Outputs
Outputs should support a re-run
The result of a tool should make the next evaluator pass more legible by improving observable evidence, not by making the narrative stronger.
Diagnostic module
Use tools by stage
Generate the missing input, then re-run the evaluator for the same stage.
Problem–Solution Fit
- If the problem is weak, every signal above it misleads.
- Generate evidence for problem before moving up.
Product–Market Fit
- If users do not return, you do not have product–market fit.
- Generate evidence for product before moving up.
Business Model Fit
- If margins break at scale, the model fails.
- Generate evidence for business model before moving up.
Diagnostic module
Problem stage tools
Use these to generate scoreable inputs for Problem–Solution Fit.
User Survey Generator
GENERATEDesign behaviour-based surveys that reveal real problems, frequency, and current alternatives.
Improves
Problem–Solution Fit: Problem existence, frequency evidence
User Interview Generator
GENERATECreate structured interviews that uncover real pain, past behaviour, and failed solutions.
Improves
Problem–Solution Fit: Observed problem intensity and user context
Prototype Test Generator
BUILDTest real user reactions to your solution without explanation or selling.
Improves
Problem–Solution Fit: Solution reaction and behavioural validation
Diagnostic module
How to use them
Keep the flow strict. Tools improve evidence. They do not replace evaluation.
Run the loop in order
- Run the evaluator first.
- Identify what still fails or scores zero.
- Generate evidence for that exact gap.
- Re-run the evaluator before moving stages.
Diagnostic module
System references
The tool layer belongs inside the same operational graph as the evaluators, report, and evidence definitions.
Diagnostic module
Command path
Most teams should run Problem–Solution Fit before using any tool.
The evaluator tells you which evidence is missing. The tool should answer that gap, not create more noise.
Go to Problem–Solution FitPrimary action
Generate evidence only after the stage tells you what is missing.
Start with the evaluator, then use the right tool to improve the next re-run.